1 /** @file inifcns_nstdsums.cpp
3 * Implementation of some special functions that have a representation as nested sums.
6 * classical polylogarithm Li(n,x)
7 * multiple polylogarithm Li(lst{m_1,...,m_k},lst{x_1,...,x_k})
8 * G(lst{a_1,...,a_k},y) or G(lst{a_1,...,a_k},lst{s_1,...,s_k},y)
9 * Nielsen's generalized polylogarithm S(n,p,x)
10 * harmonic polylogarithm H(m,x) or H(lst{m_1,...,m_k},x)
11 * multiple zeta value zeta(m) or zeta(lst{m_1,...,m_k})
12 * alternating Euler sum zeta(m,s) or zeta(lst{m_1,...,m_k},lst{s_1,...,s_k})
16 * - All formulae used can be looked up in the following publications:
17 * [Kol] Nielsen's Generalized Polylogarithms, K.S.Kolbig, SIAM J.Math.Anal. 17 (1986), pp. 1232-1258.
18 * [Cra] Fast Evaluation of Multiple Zeta Sums, R.E.Crandall, Math.Comp. 67 (1998), pp. 1163-1172.
19 * [ReV] Harmonic Polylogarithms, E.Remiddi, J.A.M.Vermaseren, Int.J.Mod.Phys. A15 (2000), pp. 725-754
20 * [BBB] Special Values of Multiple Polylogarithms, J.Borwein, D.Bradley, D.Broadhurst, P.Lisonek, Trans.Amer.Math.Soc. 353/3 (2001), pp. 907-941
21 * [VSW] Numerical evaluation of multiple polylogarithms, J.Vollinga, S.Weinzierl, hep-ph/0410259
23 * - The order of parameters and arguments of Li and zeta is defined according to the nested sums
24 * representation. The parameters for H are understood as in [ReV]. They can be in expanded --- only
25 * 0, 1 and -1 --- or in compactified --- a string with zeros in front of 1 or -1 is written as a single
26 * number --- notation.
28 * - All functions can be numerically evaluated with arguments in the whole complex plane. The parameters
29 * for Li, zeta and S must be positive integers. If you want to have an alternating Euler sum, you have
30 * to give the signs of the parameters as a second argument s to zeta(m,s) containing 1 and -1.
32 * - The calculation of classical polylogarithms is speeded up by using Bernoulli numbers and
33 * look-up tables. S uses look-up tables as well. The zeta function applies the algorithms in
34 * [Cra] and [BBB] for speed up. Multiple polylogarithms use Hoelder convolution [BBB].
36 * - The functions have no means to do a series expansion into nested sums. To do this, you have to convert
37 * these functions into the appropriate objects from the nestedsums library, do the expansion and convert
40 * - Numerical testing of this implementation has been performed by doing a comparison of results
41 * between this software and the commercial M.......... 4.1. Multiple zeta values have been checked
42 * by means of evaluations into simple zeta values. Harmonic polylogarithms have been checked by
43 * comparison to S(n,p,x) for corresponding parameter combinations and by continuity checks
44 * around |x|=1 along with comparisons to corresponding zeta functions. Multiple polylogarithms were
45 * checked against H and zeta and by means of shuffle and quasi-shuffle relations.
50 * GiNaC Copyright (C) 1999-2019 Johannes Gutenberg University Mainz, Germany
52 * This program is free software; you can redistribute it and/or modify
53 * it under the terms of the GNU General Public License as published by
54 * the Free Software Foundation; either version 2 of the License, or
55 * (at your option) any later version.
57 * This program is distributed in the hope that it will be useful,
58 * but WITHOUT ANY WARRANTY; without even the implied warranty of
59 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
60 * GNU General Public License for more details.
62 * You should have received a copy of the GNU General Public License
63 * along with this program; if not, write to the Free Software
64 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
74 #include "operators.h"
77 #include "relational.h"
90 //////////////////////////////////////////////////////////////////////
92 // Classical polylogarithm Li(n,x)
96 //////////////////////////////////////////////////////////////////////
99 // anonymous namespace for helper functions
103 // lookup table for factors built from Bernoulli numbers
105 std::vector<std::vector<cln::cl_N>> Xn;
106 // initial size of Xn that should suffice for 32bit machines (must be even)
107 const int xninitsizestep = 26;
108 int xninitsize = xninitsizestep;
112 // This function calculates the X_n. The X_n are needed for speed up of classical polylogarithms.
113 // With these numbers the polylogs can be calculated as follows:
114 // Li_p (x) = \sum_{n=0}^\infty X_{p-2}(n) u^{n+1}/(n+1)! with u = -log(1-x)
115 // X_0(n) = B_n (Bernoulli numbers)
116 // X_p(n) = \sum_{k=0}^n binomial(n,k) B_{n-k} / (k+1) * X_{p-1}(k)
117 // The calculation of Xn depends on X0 and X{n-1}.
118 // X_0 is special, it holds only the non-zero Bernoulli numbers with index 2 or greater.
119 // This results in a slightly more complicated algorithm for the X_n.
120 // The first index in Xn corresponds to the index of the polylog minus 2.
121 // The second index in Xn corresponds to the index from the actual sum.
125 // calculate X_2 and higher (corresponding to Li_4 and higher)
126 std::vector<cln::cl_N> buf(xninitsize);
127 auto it = buf.begin();
129 *it = -(cln::expt(cln::cl_I(2),n+1) - 1) / cln::expt(cln::cl_I(2),n+1); // i == 1
131 for (int i=2; i<=xninitsize; i++) {
133 result = 0; // k == 0
135 result = Xn[0][i/2-1]; // k == 0
137 for (int k=1; k<i-1; k++) {
138 if ( !(((i-k) & 1) && ((i-k) > 1)) ) {
139 result = result + cln::binomial(i,k) * Xn[0][(i-k)/2-1] * Xn[n-1][k-1] / (k+1);
142 result = result - cln::binomial(i,i-1) * Xn[n-1][i-2] / 2 / i; // k == i-1
143 result = result + Xn[n-1][i-1] / (i+1); // k == i
150 // special case to handle the X_0 correct
151 std::vector<cln::cl_N> buf(xninitsize);
152 auto it = buf.begin();
154 *it = cln::cl_I(-3)/cln::cl_I(4); // i == 1
156 *it = cln::cl_I(17)/cln::cl_I(36); // i == 2
158 for (int i=3; i<=xninitsize; i++) {
160 result = -Xn[0][(i-3)/2]/2;
161 *it = (cln::binomial(i,1)/cln::cl_I(2) + cln::binomial(i,i-1)/cln::cl_I(i))*result;
164 result = Xn[0][i/2-1] + Xn[0][i/2-1]/(i+1);
165 for (int k=1; k<i/2; k++) {
166 result = result + cln::binomial(i,k*2) * Xn[0][k-1] * Xn[0][i/2-k-1] / (k*2+1);
175 std::vector<cln::cl_N> buf(xninitsize/2);
176 auto it = buf.begin();
177 for (int i=1; i<=xninitsize/2; i++) {
178 *it = bernoulli(i*2).to_cl_N();
187 // doubles the number of entries in each Xn[]
190 const int pos0 = xninitsize / 2;
192 for (int i=1; i<=xninitsizestep/2; ++i) {
193 Xn[0].push_back(bernoulli((i+pos0)*2).to_cl_N());
196 int xend = xninitsize + xninitsizestep;
199 for (int i=xninitsize+1; i<=xend; ++i) {
201 result = -Xn[0][(i-3)/2]/2;
202 Xn[1].push_back((cln::binomial(i,1)/cln::cl_I(2) + cln::binomial(i,i-1)/cln::cl_I(i))*result);
204 result = Xn[0][i/2-1] + Xn[0][i/2-1]/(i+1);
205 for (int k=1; k<i/2; k++) {
206 result = result + cln::binomial(i,k*2) * Xn[0][k-1] * Xn[0][i/2-k-1] / (k*2+1);
208 Xn[1].push_back(result);
212 for (size_t n=2; n<Xn.size(); ++n) {
213 for (int i=xninitsize+1; i<=xend; ++i) {
215 result = 0; // k == 0
217 result = Xn[0][i/2-1]; // k == 0
219 for (int k=1; k<i-1; ++k) {
220 if ( !(((i-k) & 1) && ((i-k) > 1)) ) {
221 result = result + cln::binomial(i,k) * Xn[0][(i-k)/2-1] * Xn[n-1][k-1] / (k+1);
224 result = result - cln::binomial(i,i-1) * Xn[n-1][i-2] / 2 / i; // k == i-1
225 result = result + Xn[n-1][i-1] / (i+1); // k == i
226 Xn[n].push_back(result);
230 xninitsize += xninitsizestep;
234 // calculates Li(2,x) without Xn
235 cln::cl_N Li2_do_sum(const cln::cl_N& x)
239 cln::cl_N num = x * cln::cl_float(1, cln::float_format(Digits));
240 cln::cl_I den = 1; // n^2 = 1
245 den = den + i; // n^2 = 4, 9, 16, ...
247 res = res + num / den;
248 } while (res != resbuf);
253 // calculates Li(2,x) with Xn
254 cln::cl_N Li2_do_sum_Xn(const cln::cl_N& x)
256 std::vector<cln::cl_N>::const_iterator it = Xn[0].begin();
257 std::vector<cln::cl_N>::const_iterator xend = Xn[0].end();
258 cln::cl_N u = -cln::log(1-x);
259 cln::cl_N factor = u * cln::cl_float(1, cln::float_format(Digits));
260 cln::cl_N uu = cln::square(u);
261 cln::cl_N res = u - uu/4;
266 factor = factor * uu / (2*i * (2*i+1));
267 res = res + (*it) * factor;
271 it = Xn[0].begin() + (i-1);
274 } while (res != resbuf);
279 // calculates Li(n,x), n>2 without Xn
280 cln::cl_N Lin_do_sum(int n, const cln::cl_N& x)
282 cln::cl_N factor = x * cln::cl_float(1, cln::float_format(Digits));
289 res = res + factor / cln::expt(cln::cl_I(i),n);
291 } while (res != resbuf);
296 // calculates Li(n,x), n>2 with Xn
297 cln::cl_N Lin_do_sum_Xn(int n, const cln::cl_N& x)
299 std::vector<cln::cl_N>::const_iterator it = Xn[n-2].begin();
300 std::vector<cln::cl_N>::const_iterator xend = Xn[n-2].end();
301 cln::cl_N u = -cln::log(1-x);
302 cln::cl_N factor = u * cln::cl_float(1, cln::float_format(Digits));
308 factor = factor * u / i;
309 res = res + (*it) * factor;
313 it = Xn[n-2].begin() + (i-2);
314 xend = Xn[n-2].end();
316 } while (res != resbuf);
321 // forward declaration needed by function Li_projection and C below
322 const cln::cl_N S_num(int n, int p, const cln::cl_N& x);
325 // helper function for classical polylog Li
326 cln::cl_N Li_projection(int n, const cln::cl_N& x, const cln::float_format_t& prec)
328 // treat n=2 as special case
330 // check if precalculated X0 exists
335 if (cln::realpart(x) < 0.5) {
336 // choose the faster algorithm
337 // the switching point was empirically determined. the optimal point
338 // depends on hardware, Digits, ... so an approx value is okay.
339 // it solves also the problem with precision due to the u=-log(1-x) transformation
340 if (cln::abs(x) < 0.25) {
341 return Li2_do_sum(x);
343 // Li2_do_sum practically doesn't converge near x == ±I
344 return Li2_do_sum_Xn(x);
347 // choose the faster algorithm
348 if (cln::abs(cln::realpart(x)) > 0.75) {
352 return -Li2_do_sum(1-x) - cln::log(x) * cln::log(1-x) + cln::zeta(2);
355 return -Li2_do_sum_Xn(1-x) - cln::log(x) * cln::log(1-x) + cln::zeta(2);
359 // check if precalculated Xn exist
361 for (int i=xnsize; i<n-1; i++) {
366 if (cln::realpart(x) < 0.5) {
367 // choose the faster algorithm
368 // with n>=12 the "normal" summation always wins against the method with Xn
369 if ((cln::abs(x) < 0.3) || (n >= 12)) {
370 return Lin_do_sum(n, x);
372 // Li2_do_sum practically doesn't converge near x == ±I
373 return Lin_do_sum_Xn(n, x);
376 cln::cl_N result = 0;
377 if ( x != 1 ) result = -cln::expt(cln::log(x), n-1) * cln::log(1-x) / cln::factorial(n-1);
378 for (int j=0; j<n-1; j++) {
379 result = result + (S_num(n-j-1, 1, 1) - S_num(1, n-j-1, 1-x))
380 * cln::expt(cln::log(x), j) / cln::factorial(j);
387 // helper function for classical polylog Li
388 const cln::cl_N Lin_numeric(const int n, const cln::cl_N& x)
392 return -cln::log(1-x);
403 return -(1-cln::expt(cln::cl_I(2),1-n)) * cln::zeta(n);
405 if (cln::abs(realpart(x)) < 0.4 && cln::abs(cln::abs(x)-1) < 0.01) {
406 cln::cl_N result = -cln::expt(cln::log(x), n-1) * cln::log(1-x) / cln::factorial(n-1);
407 for (int j=0; j<n-1; j++) {
408 result = result + (S_num(n-j-1, 1, 1) - S_num(1, n-j-1, 1-x))
409 * cln::expt(cln::log(x), j) / cln::factorial(j);
414 // what is the desired float format?
415 // first guess: default format
416 cln::float_format_t prec = cln::default_float_format;
417 const cln::cl_N value = x;
418 // second guess: the argument's format
419 if (!instanceof(realpart(x), cln::cl_RA_ring))
420 prec = cln::float_format(cln::the<cln::cl_F>(cln::realpart(value)));
421 else if (!instanceof(imagpart(x), cln::cl_RA_ring))
422 prec = cln::float_format(cln::the<cln::cl_F>(cln::imagpart(value)));
425 if (cln::abs(value) > 1) {
426 cln::cl_N result = -cln::expt(cln::log(-value),n) / cln::factorial(n);
427 // check if argument is complex. if it is real, the new polylog has to be conjugated.
428 if (cln::zerop(cln::imagpart(value))) {
430 result = result + conjugate(Li_projection(n, cln::recip(value), prec));
433 result = result - conjugate(Li_projection(n, cln::recip(value), prec));
438 result = result + Li_projection(n, cln::recip(value), prec);
441 result = result - Li_projection(n, cln::recip(value), prec);
445 for (int j=0; j<n-1; j++) {
446 add = add + (1+cln::expt(cln::cl_I(-1),n-j)) * (1-cln::expt(cln::cl_I(2),1-n+j))
447 * Lin_numeric(n-j,1) * cln::expt(cln::log(-value),j) / cln::factorial(j);
449 result = result - add;
453 return Li_projection(n, value, prec);
458 } // end of anonymous namespace
461 //////////////////////////////////////////////////////////////////////
463 // Multiple polylogarithm Li(n,x)
467 //////////////////////////////////////////////////////////////////////
470 // anonymous namespace for helper function
474 // performs the actual series summation for multiple polylogarithms
475 cln::cl_N multipleLi_do_sum(const std::vector<int>& s, const std::vector<cln::cl_N>& x)
477 // ensure all x <> 0.
478 for (const auto & it : x) {
479 if (it == 0) return cln::cl_float(0, cln::float_format(Digits));
482 const int j = s.size();
483 bool flag_accidental_zero = false;
485 std::vector<cln::cl_N> t(j);
486 cln::cl_F one = cln::cl_float(1, cln::float_format(Digits));
493 t[j-1] = t[j-1] + cln::expt(x[j-1], q) / cln::expt(cln::cl_I(q),s[j-1]) * one;
494 for (int k=j-2; k>=0; k--) {
495 t[k] = t[k] + t[k+1] * cln::expt(x[k], q+j-1-k) / cln::expt(cln::cl_I(q+j-1-k), s[k]);
498 t[j-1] = t[j-1] + cln::expt(x[j-1], q) / cln::expt(cln::cl_I(q),s[j-1]) * one;
499 for (int k=j-2; k>=0; k--) {
500 flag_accidental_zero = cln::zerop(t[k+1]);
501 t[k] = t[k] + t[k+1] * cln::expt(x[k], q+j-1-k) / cln::expt(cln::cl_I(q+j-1-k), s[k]);
503 } while ( (t[0] != t0buf) || cln::zerop(t[0]) || flag_accidental_zero );
509 // forward declaration for Li_eval()
510 lst convert_parameter_Li_to_H(const lst& m, const lst& x, ex& pf);
513 // type used by the transformation functions for G
514 typedef std::vector<int> Gparameter;
517 // G_eval1-function for G transformations
518 ex G_eval1(int a, int scale, const exvector& gsyms)
521 const ex& scs = gsyms[std::abs(scale)];
522 const ex& as = gsyms[std::abs(a)];
524 return -log(1 - scs/as);
529 return log(gsyms[std::abs(scale)]);
534 // G_eval-function for G transformations
535 ex G_eval(const Gparameter& a, int scale, const exvector& gsyms)
537 // check for properties of G
538 ex sc = gsyms[std::abs(scale)];
540 bool all_zero = true;
541 bool all_ones = true;
543 for (const auto & it : a) {
545 const ex sym = gsyms[std::abs(it)];
559 // care about divergent G: shuffle to separate divergencies that will be canceled
560 // later on in the transformation
561 if (newa.nops() > 1 && newa.op(0) == sc && !all_ones && a.front()!=0) {
563 Gparameter short_a(a.begin()+1, a.end());
564 ex result = G_eval1(a.front(), scale, gsyms) * G_eval(short_a, scale, gsyms);
566 auto it = short_a.begin();
567 advance(it, count_ones-1);
568 for (; it != short_a.end(); ++it) {
570 Gparameter newa(short_a.begin(), it);
572 newa.push_back(a[0]);
573 newa.insert(newa.end(), it+1, short_a.end());
574 result -= G_eval(newa, scale, gsyms);
576 return result / count_ones;
579 // G({1,...,1};y) -> G({1};y)^k / k!
580 if (all_ones && a.size() > 1) {
581 return pow(G_eval1(a.front(),scale, gsyms), count_ones) / factorial(count_ones);
584 // G({0,...,0};y) -> log(y)^k / k!
586 return pow(log(gsyms[std::abs(scale)]), a.size()) / factorial(a.size());
589 // no special cases anymore -> convert it into Li
592 ex argbuf = gsyms[std::abs(scale)];
594 for (const auto & it : a) {
596 const ex& sym = gsyms[std::abs(it)];
597 x.append(argbuf / sym);
605 return pow(-1, x.nops()) * Li(m, x);
608 // convert back to standard G-function, keep information on small imaginary parts
609 ex G_eval_to_G(const Gparameter& a, int scale, const exvector& gsyms)
613 for (const auto & it : a) {
615 z.append(gsyms[std::abs(it)]);
626 return G(z,s,gsyms[std::abs(scale)]);
630 // converts data for G: pending_integrals -> a
631 Gparameter convert_pending_integrals_G(const Gparameter& pending_integrals)
633 GINAC_ASSERT(pending_integrals.size() != 1);
635 if (pending_integrals.size() > 0) {
636 // get rid of the first element, which would stand for the new upper limit
637 Gparameter new_a(pending_integrals.begin()+1, pending_integrals.end());
640 // just return empty parameter list
647 // check the parameters a and scale for G and return information about convergence, depth, etc.
648 // convergent : true if G(a,scale) is convergent
649 // depth : depth of G(a,scale)
650 // trailing_zeros : number of trailing zeros of a
651 // min_it : iterator of a pointing on the smallest element in a
652 Gparameter::const_iterator check_parameter_G(const Gparameter& a, int scale,
653 bool& convergent, int& depth, int& trailing_zeros, Gparameter::const_iterator& min_it)
659 auto lastnonzero = a.end();
660 for (auto it = a.begin(); it != a.end(); ++it) {
661 if (std::abs(*it) > 0) {
665 if (std::abs(*it) < scale) {
667 if ((min_it == a.end()) || (std::abs(*it) < std::abs(*min_it))) {
675 if (lastnonzero == a.end())
677 return ++lastnonzero;
681 // add scale to pending_integrals if pending_integrals is empty
682 Gparameter prepare_pending_integrals(const Gparameter& pending_integrals, int scale)
684 GINAC_ASSERT(pending_integrals.size() != 1);
686 if (pending_integrals.size() > 0) {
687 return pending_integrals;
689 Gparameter new_pending_integrals;
690 new_pending_integrals.push_back(scale);
691 return new_pending_integrals;
696 // handles trailing zeroes for an otherwise convergent integral
697 ex trailing_zeros_G(const Gparameter& a, int scale, const exvector& gsyms)
700 int depth, trailing_zeros;
701 Gparameter::const_iterator last, dummyit;
702 last = check_parameter_G(a, scale, convergent, depth, trailing_zeros, dummyit);
704 GINAC_ASSERT(convergent);
706 if ((trailing_zeros > 0) && (depth > 0)) {
708 Gparameter new_a(a.begin(), a.end()-1);
709 result += G_eval1(0, scale, gsyms) * trailing_zeros_G(new_a, scale, gsyms);
710 for (auto it = a.begin(); it != last; ++it) {
711 Gparameter new_a(a.begin(), it);
713 new_a.insert(new_a.end(), it, a.end()-1);
714 result -= trailing_zeros_G(new_a, scale, gsyms);
717 return result / trailing_zeros;
719 return G_eval(a, scale, gsyms);
724 // G transformation [VSW] (57),(58)
725 ex depth_one_trafo_G(const Gparameter& pending_integrals, const Gparameter& a, int scale, const exvector& gsyms)
727 // pendint = ( y1, b1, ..., br )
728 // a = ( 0, ..., 0, amin )
731 // int_0^y1 ds1/(s1-b1) ... int dsr/(sr-br) G(0, ..., 0, sr; y2)
732 // where sr replaces amin
734 GINAC_ASSERT(a.back() != 0);
735 GINAC_ASSERT(a.size() > 0);
738 Gparameter new_pending_integrals = prepare_pending_integrals(pending_integrals, std::abs(a.back()));
739 const int psize = pending_integrals.size();
742 // G(sr_{+-}; y2 ) = G(y2_{-+}; sr) - G(0; sr) + ln(-y2_{-+})
747 result += log(gsyms[ex_to<numeric>(scale).to_int()]);
749 new_pending_integrals.push_back(-scale);
752 new_pending_integrals.push_back(scale);
756 result *= trailing_zeros_G(convert_pending_integrals_G(pending_integrals),
757 pending_integrals.front(),
762 result += trailing_zeros_G(convert_pending_integrals_G(new_pending_integrals),
763 new_pending_integrals.front(),
767 new_pending_integrals.back() = 0;
768 result -= trailing_zeros_G(convert_pending_integrals_G(new_pending_integrals),
769 new_pending_integrals.front(),
776 // G_m(sr_{+-}; y2) = -zeta_m + int_0^y2 dt/t G_{m-1}( (1/y2)_{+-}; 1/t )
777 // - int_0^sr dt/t G_{m-1}( (1/y2)_{+-}; 1/t )
780 result -= zeta(a.size());
782 result *= trailing_zeros_G(convert_pending_integrals_G(pending_integrals),
783 pending_integrals.front(),
787 // term int_0^sr dt/t G_{m-1}( (1/y2)_{+-}; 1/t )
788 // = int_0^sr dt/t G_{m-1}( t_{+-}; y2 )
789 Gparameter new_a(a.begin()+1, a.end());
790 new_pending_integrals.push_back(0);
791 result -= depth_one_trafo_G(new_pending_integrals, new_a, scale, gsyms);
793 // term int_0^y2 dt/t G_{m-1}( (1/y2)_{+-}; 1/t )
794 // = int_0^y2 dt/t G_{m-1}( t_{+-}; y2 )
795 Gparameter new_pending_integrals_2;
796 new_pending_integrals_2.push_back(scale);
797 new_pending_integrals_2.push_back(0);
799 result += trailing_zeros_G(convert_pending_integrals_G(pending_integrals),
800 pending_integrals.front(),
802 * depth_one_trafo_G(new_pending_integrals_2, new_a, scale, gsyms);
804 result += depth_one_trafo_G(new_pending_integrals_2, new_a, scale, gsyms);
811 // forward declaration
812 ex shuffle_G(const Gparameter & a0, const Gparameter & a1, const Gparameter & a2,
813 const Gparameter& pendint, const Gparameter& a_old, int scale,
814 const exvector& gsyms, bool flag_trailing_zeros_only);
817 // G transformation [VSW]
818 ex G_transform(const Gparameter& pendint, const Gparameter& a, int scale,
819 const exvector& gsyms, bool flag_trailing_zeros_only)
821 // main recursion routine
823 // pendint = ( y1, b1, ..., br )
824 // a = ( a1, ..., amin, ..., aw )
827 // int_0^y1 ds1/(s1-b1) ... int dsr/(sr-br) G(a1,...,sr,...,aw,y2)
828 // where sr replaces amin
830 // find smallest alpha, determine depth and trailing zeros, and check for convergence
832 int depth, trailing_zeros;
833 Gparameter::const_iterator min_it;
834 auto firstzero = check_parameter_G(a, scale, convergent, depth, trailing_zeros, min_it);
835 int min_it_pos = distance(a.begin(), min_it);
837 // special case: all a's are zero
844 result = G_eval(a, scale, gsyms);
846 if (pendint.size() > 0) {
847 result *= trailing_zeros_G(convert_pending_integrals_G(pendint),
854 // handle trailing zeros
855 if (trailing_zeros > 0) {
857 Gparameter new_a(a.begin(), a.end()-1);
858 result += G_eval1(0, scale, gsyms) * G_transform(pendint, new_a, scale, gsyms, flag_trailing_zeros_only);
859 for (auto it = a.begin(); it != firstzero; ++it) {
860 Gparameter new_a(a.begin(), it);
862 new_a.insert(new_a.end(), it, a.end()-1);
863 result -= G_transform(pendint, new_a, scale, gsyms, flag_trailing_zeros_only);
865 return result / trailing_zeros;
868 // flag_trailing_zeros_only: in this case we don't have pending integrals
869 if (flag_trailing_zeros_only)
870 return G_eval_to_G(a, scale, gsyms);
874 if (pendint.size() > 0) {
875 return G_eval(convert_pending_integrals_G(pendint),
876 pendint.front(), gsyms) *
877 G_eval(a, scale, gsyms);
879 return G_eval(a, scale, gsyms);
883 // call basic transformation for depth equal one
885 return depth_one_trafo_G(pendint, a, scale, gsyms);
889 // int_0^y1 ds1/(s1-b1) ... int dsr/(sr-br) G(a1,...,sr,...,aw,y2)
890 // = int_0^y1 ds1/(s1-b1) ... int dsr/(sr-br) G(a1,...,0,...,aw,y2)
891 // + int_0^y1 ds1/(s1-b1) ... int dsr/(sr-br) int_0^{sr} ds_{r+1} d/ds_{r+1} G(a1,...,s_{r+1},...,aw,y2)
893 // smallest element in last place
894 if (min_it + 1 == a.end()) {
895 do { --min_it; } while (*min_it == 0);
897 Gparameter a1(a.begin(),min_it+1);
898 Gparameter a2(min_it+1,a.end());
900 ex result = G_transform(pendint, a2, scale, gsyms, flag_trailing_zeros_only)*
901 G_transform(empty, a1, scale, gsyms, flag_trailing_zeros_only);
903 result -= shuffle_G(empty, a1, a2, pendint, a, scale, gsyms, flag_trailing_zeros_only);
908 Gparameter::iterator changeit;
910 // first term G(a_1,..,0,...,a_w;a_0)
911 Gparameter new_pendint = prepare_pending_integrals(pendint, a[min_it_pos]);
912 Gparameter new_a = a;
913 new_a[min_it_pos] = 0;
914 ex result = G_transform(empty, new_a, scale, gsyms, flag_trailing_zeros_only);
915 if (pendint.size() > 0) {
916 result *= trailing_zeros_G(convert_pending_integrals_G(pendint),
917 pendint.front(), gsyms);
921 changeit = new_a.begin() + min_it_pos;
922 changeit = new_a.erase(changeit);
923 if (changeit != new_a.begin()) {
924 // smallest in the middle
925 new_pendint.push_back(*changeit);
926 result -= trailing_zeros_G(convert_pending_integrals_G(new_pendint),
927 new_pendint.front(), gsyms)*
928 G_transform(empty, new_a, scale, gsyms, flag_trailing_zeros_only);
929 int buffer = *changeit;
931 result += G_transform(new_pendint, new_a, scale, gsyms, flag_trailing_zeros_only);
933 new_pendint.pop_back();
935 new_pendint.push_back(*changeit);
936 result += trailing_zeros_G(convert_pending_integrals_G(new_pendint),
937 new_pendint.front(), gsyms)*
938 G_transform(empty, new_a, scale, gsyms, flag_trailing_zeros_only);
940 result -= G_transform(new_pendint, new_a, scale, gsyms, flag_trailing_zeros_only);
942 // smallest at the front
943 new_pendint.push_back(scale);
944 result += trailing_zeros_G(convert_pending_integrals_G(new_pendint),
945 new_pendint.front(), gsyms)*
946 G_transform(empty, new_a, scale, gsyms, flag_trailing_zeros_only);
947 new_pendint.back() = *changeit;
948 result -= trailing_zeros_G(convert_pending_integrals_G(new_pendint),
949 new_pendint.front(), gsyms)*
950 G_transform(empty, new_a, scale, gsyms, flag_trailing_zeros_only);
952 result += G_transform(new_pendint, new_a, scale, gsyms, flag_trailing_zeros_only);
958 // shuffles the two parameter list a1 and a2 and calls G_transform for every term except
959 // for the one that is equal to a_old
960 ex shuffle_G(const Gparameter & a0, const Gparameter & a1, const Gparameter & a2,
961 const Gparameter& pendint, const Gparameter& a_old, int scale,
962 const exvector& gsyms, bool flag_trailing_zeros_only)
964 if (a1.size()==0 && a2.size()==0) {
965 // veto the one configuration we don't want
966 if ( a0 == a_old ) return 0;
968 return G_transform(pendint, a0, scale, gsyms, flag_trailing_zeros_only);
974 aa0.insert(aa0.end(),a1.begin(),a1.end());
975 return shuffle_G(aa0, empty, empty, pendint, a_old, scale, gsyms, flag_trailing_zeros_only);
981 aa0.insert(aa0.end(),a2.begin(),a2.end());
982 return shuffle_G(aa0, empty, empty, pendint, a_old, scale, gsyms, flag_trailing_zeros_only);
985 Gparameter a1_removed(a1.begin()+1,a1.end());
986 Gparameter a2_removed(a2.begin()+1,a2.end());
991 a01.push_back( a1[0] );
992 a02.push_back( a2[0] );
994 return shuffle_G(a01, a1_removed, a2, pendint, a_old, scale, gsyms, flag_trailing_zeros_only)
995 + shuffle_G(a02, a1, a2_removed, pendint, a_old, scale, gsyms, flag_trailing_zeros_only);
998 // handles the transformations and the numerical evaluation of G
999 // the parameter x, s and y must only contain numerics
1001 G_numeric(const std::vector<cln::cl_N>& x, const std::vector<int>& s,
1002 const cln::cl_N& y);
1004 // do acceleration transformation (hoelder convolution [BBB])
1005 // the parameter x, s and y must only contain numerics
1007 G_do_hoelder(std::vector<cln::cl_N> x, /* yes, it's passed by value */
1008 const std::vector<int>& s, const cln::cl_N& y)
1011 const std::size_t size = x.size();
1012 for (std::size_t i = 0; i < size; ++i)
1015 for (std::size_t r = 0; r <= size; ++r) {
1016 cln::cl_N buffer(1 & r ? -1 : 1);
1021 for (std::size_t i = 0; i < size; ++i) {
1022 if (x[i] == cln::cl_RA(1)/p) {
1023 p = p/2 + cln::cl_RA(3)/2;
1029 cln::cl_RA q = p/(p-1);
1030 std::vector<cln::cl_N> qlstx;
1031 std::vector<int> qlsts;
1032 for (std::size_t j = r; j >= 1; --j) {
1033 qlstx.push_back(cln::cl_N(1) - x[j-1]);
1034 if (imagpart(x[j-1])==0 && realpart(x[j-1]) >= 1) {
1037 qlsts.push_back(-s[j-1]);
1040 if (qlstx.size() > 0) {
1041 buffer = buffer*G_numeric(qlstx, qlsts, 1/q);
1043 std::vector<cln::cl_N> plstx;
1044 std::vector<int> plsts;
1045 for (std::size_t j = r+1; j <= size; ++j) {
1046 plstx.push_back(x[j-1]);
1047 plsts.push_back(s[j-1]);
1049 if (plstx.size() > 0) {
1050 buffer = buffer*G_numeric(plstx, plsts, 1/p);
1052 result = result + buffer;
1057 class less_object_for_cl_N
1060 bool operator() (const cln::cl_N & a, const cln::cl_N & b) const
1063 if (abs(a) != abs(b))
1064 return (abs(a) < abs(b)) ? true : false;
1067 if (phase(a) != phase(b))
1068 return (phase(a) < phase(b)) ? true : false;
1070 // equal, therefore "less" is not true
1076 // convergence transformation, used for numerical evaluation of G function.
1077 // the parameter x, s and y must only contain numerics
1079 G_do_trafo(const std::vector<cln::cl_N>& x, const std::vector<int>& s,
1080 const cln::cl_N& y, bool flag_trailing_zeros_only)
1082 // sort (|x|<->position) to determine indices
1083 typedef std::multimap<cln::cl_N, std::size_t, less_object_for_cl_N> sortmap_t;
1085 std::size_t size = 0;
1086 for (std::size_t i = 0; i < x.size(); ++i) {
1088 sortmap.insert(std::make_pair(x[i], i));
1092 // include upper limit (scale)
1093 sortmap.insert(std::make_pair(y, x.size()));
1095 // generate missing dummy-symbols
1097 // holding dummy-symbols for the G/Li transformations
1099 gsyms.push_back(symbol("GSYMS_ERROR"));
1100 cln::cl_N lastentry(0);
1101 for (sortmap_t::const_iterator it = sortmap.begin(); it != sortmap.end(); ++it) {
1102 if (it != sortmap.begin()) {
1103 if (it->second < x.size()) {
1104 if (x[it->second] == lastentry) {
1105 gsyms.push_back(gsyms.back());
1109 if (y == lastentry) {
1110 gsyms.push_back(gsyms.back());
1115 std::ostringstream os;
1117 gsyms.push_back(symbol(os.str()));
1119 if (it->second < x.size()) {
1120 lastentry = x[it->second];
1126 // fill position data according to sorted indices and prepare substitution list
1127 Gparameter a(x.size());
1129 std::size_t pos = 1;
1131 for (sortmap_t::const_iterator it = sortmap.begin(); it != sortmap.end(); ++it) {
1132 if (it->second < x.size()) {
1133 if (s[it->second] > 0) {
1134 a[it->second] = pos;
1136 a[it->second] = -int(pos);
1138 subslst[gsyms[pos]] = numeric(x[it->second]);
1141 subslst[gsyms[pos]] = numeric(y);
1146 // do transformation
1148 ex result = G_transform(pendint, a, scale, gsyms, flag_trailing_zeros_only);
1149 // replace dummy symbols with their values
1150 result = result.expand();
1151 result = result.subs(subslst).evalf();
1152 if (!is_a<numeric>(result))
1153 throw std::logic_error("G_do_trafo: G_transform returned non-numeric result");
1155 cln::cl_N ret = ex_to<numeric>(result).to_cl_N();
1159 // handles the transformations and the numerical evaluation of G
1160 // the parameter x, s and y must only contain numerics
1162 G_numeric(const std::vector<cln::cl_N>& x, const std::vector<int>& s,
1165 // check for convergence and necessary accelerations
1166 bool need_trafo = false;
1167 bool need_hoelder = false;
1168 bool have_trailing_zero = false;
1169 std::size_t depth = 0;
1170 for (auto & xi : x) {
1173 const cln::cl_N x_y = abs(xi) - y;
1174 if (instanceof(x_y, cln::cl_R_ring) &&
1175 realpart(x_y) < cln::least_negative_float(cln::float_format(Digits - 2)))
1178 if (abs(abs(xi/y) - 1) < 0.01)
1179 need_hoelder = true;
1182 if (zerop(x.back())) {
1183 have_trailing_zero = true;
1187 if (depth == 1 && x.size() == 2 && !need_trafo)
1188 return - Li_projection(2, y/x[1], cln::float_format(Digits));
1190 // do acceleration transformation (hoelder convolution [BBB])
1191 if (need_hoelder && !have_trailing_zero)
1192 return G_do_hoelder(x, s, y);
1194 // convergence transformation
1196 return G_do_trafo(x, s, y, have_trailing_zero);
1199 std::vector<cln::cl_N> newx;
1200 newx.reserve(x.size());
1202 m.reserve(x.size());
1205 cln::cl_N factor = y;
1206 for (auto & xi : x) {
1210 newx.push_back(factor/xi);
1212 m.push_back(mcount);
1218 return sign*multipleLi_do_sum(m, newx);
1222 ex mLi_numeric(const lst& m, const lst& x)
1224 // let G_numeric do the transformation
1225 std::vector<cln::cl_N> newx;
1226 newx.reserve(x.nops());
1228 s.reserve(x.nops());
1229 cln::cl_N factor(1);
1230 for (auto itm = m.begin(), itx = x.begin(); itm != m.end(); ++itm, ++itx) {
1231 for (int i = 1; i < *itm; ++i) {
1232 newx.push_back(cln::cl_N(0));
1235 const cln::cl_N xi = ex_to<numeric>(*itx).to_cl_N();
1237 newx.push_back(factor);
1238 if ( !instanceof(factor, cln::cl_R_ring) && imagpart(factor) < 0 ) {
1245 return numeric(cln::cl_N(1 & m.nops() ? - 1 : 1)*G_numeric(newx, s, cln::cl_N(1)));
1249 } // end of anonymous namespace
1252 //////////////////////////////////////////////////////////////////////
1254 // Generalized multiple polylogarithm G(x, y) and G(x, s, y)
1258 //////////////////////////////////////////////////////////////////////
1261 static ex G2_evalf(const ex& x_, const ex& y)
1263 if ((!y.info(info_flags::numeric)) || (!y.info(info_flags::positive))) {
1264 return G(x_, y).hold();
1266 lst x = is_a<lst>(x_) ? ex_to<lst>(x_) : lst{x_};
1267 if (x.nops() == 0) {
1271 return G(x_, y).hold();
1274 s.reserve(x.nops());
1275 bool all_zero = true;
1276 for (const auto & it : x) {
1277 if (!it.info(info_flags::numeric)) {
1278 return G(x_, y).hold();
1283 if ( !ex_to<numeric>(it).is_real() && ex_to<numeric>(it).imag() < 0 ) {
1291 return pow(log(y), x.nops()) / factorial(x.nops());
1293 std::vector<cln::cl_N> xv;
1294 xv.reserve(x.nops());
1295 for (const auto & it : x)
1296 xv.push_back(ex_to<numeric>(it).to_cl_N());
1297 cln::cl_N result = G_numeric(xv, s, ex_to<numeric>(y).to_cl_N());
1298 return numeric(result);
1302 static ex G2_eval(const ex& x_, const ex& y)
1304 //TODO eval to MZV or H or S or Lin
1306 if ((!y.info(info_flags::numeric)) || (!y.info(info_flags::positive))) {
1307 return G(x_, y).hold();
1309 lst x = is_a<lst>(x_) ? ex_to<lst>(x_) : lst{x_};
1310 if (x.nops() == 0) {
1314 return G(x_, y).hold();
1317 s.reserve(x.nops());
1318 bool all_zero = true;
1319 bool crational = true;
1320 for (const auto & it : x) {
1321 if (!it.info(info_flags::numeric)) {
1322 return G(x_, y).hold();
1324 if (!it.info(info_flags::crational)) {
1330 if ( !ex_to<numeric>(it).is_real() && ex_to<numeric>(it).imag() < 0 ) {
1338 return pow(log(y), x.nops()) / factorial(x.nops());
1340 if (!y.info(info_flags::crational)) {
1344 return G(x_, y).hold();
1346 std::vector<cln::cl_N> xv;
1347 xv.reserve(x.nops());
1348 for (const auto & it : x)
1349 xv.push_back(ex_to<numeric>(it).to_cl_N());
1350 cln::cl_N result = G_numeric(xv, s, ex_to<numeric>(y).to_cl_N());
1351 return numeric(result);
1355 // option do_not_evalf_params() removed.
1356 unsigned G2_SERIAL::serial = function::register_new(function_options("G", 2).
1357 evalf_func(G2_evalf).
1361 // derivative_func(G2_deriv).
1362 // print_func<print_latex>(G2_print_latex).
1365 static ex G3_evalf(const ex& x_, const ex& s_, const ex& y)
1367 if ((!y.info(info_flags::numeric)) || (!y.info(info_flags::positive))) {
1368 return G(x_, s_, y).hold();
1370 lst x = is_a<lst>(x_) ? ex_to<lst>(x_) : lst{x_};
1371 lst s = is_a<lst>(s_) ? ex_to<lst>(s_) : lst{s_};
1372 if (x.nops() != s.nops()) {
1373 return G(x_, s_, y).hold();
1375 if (x.nops() == 0) {
1379 return G(x_, s_, y).hold();
1381 std::vector<int> sn;
1382 sn.reserve(s.nops());
1383 bool all_zero = true;
1384 for (auto itx = x.begin(), its = s.begin(); itx != x.end(); ++itx, ++its) {
1385 if (!(*itx).info(info_flags::numeric)) {
1386 return G(x_, y).hold();
1388 if (!(*its).info(info_flags::real)) {
1389 return G(x_, y).hold();
1394 if ( ex_to<numeric>(*itx).is_real() ) {
1395 if ( ex_to<numeric>(*itx).is_positive() ) {
1407 if ( ex_to<numeric>(*itx).imag() > 0 ) {
1416 return pow(log(y), x.nops()) / factorial(x.nops());
1418 std::vector<cln::cl_N> xn;
1419 xn.reserve(x.nops());
1420 for (const auto & it : x)
1421 xn.push_back(ex_to<numeric>(it).to_cl_N());
1422 cln::cl_N result = G_numeric(xn, sn, ex_to<numeric>(y).to_cl_N());
1423 return numeric(result);
1427 static ex G3_eval(const ex& x_, const ex& s_, const ex& y)
1429 //TODO eval to MZV or H or S or Lin
1431 if ((!y.info(info_flags::numeric)) || (!y.info(info_flags::positive))) {
1432 return G(x_, s_, y).hold();
1434 lst x = is_a<lst>(x_) ? ex_to<lst>(x_) : lst{x_};
1435 lst s = is_a<lst>(s_) ? ex_to<lst>(s_) : lst{s_};
1436 if (x.nops() != s.nops()) {
1437 return G(x_, s_, y).hold();
1439 if (x.nops() == 0) {
1443 return G(x_, s_, y).hold();
1445 std::vector<int> sn;
1446 sn.reserve(s.nops());
1447 bool all_zero = true;
1448 bool crational = true;
1449 for (auto itx = x.begin(), its = s.begin(); itx != x.end(); ++itx, ++its) {
1450 if (!(*itx).info(info_flags::numeric)) {
1451 return G(x_, s_, y).hold();
1453 if (!(*its).info(info_flags::real)) {
1454 return G(x_, s_, y).hold();
1456 if (!(*itx).info(info_flags::crational)) {
1462 if ( ex_to<numeric>(*itx).is_real() ) {
1463 if ( ex_to<numeric>(*itx).is_positive() ) {
1475 if ( ex_to<numeric>(*itx).imag() > 0 ) {
1484 return pow(log(y), x.nops()) / factorial(x.nops());
1486 if (!y.info(info_flags::crational)) {
1490 return G(x_, s_, y).hold();
1492 std::vector<cln::cl_N> xn;
1493 xn.reserve(x.nops());
1494 for (const auto & it : x)
1495 xn.push_back(ex_to<numeric>(it).to_cl_N());
1496 cln::cl_N result = G_numeric(xn, sn, ex_to<numeric>(y).to_cl_N());
1497 return numeric(result);
1501 // option do_not_evalf_params() removed.
1502 // This is safe: in the code above it only matters if s_ > 0 or s_ < 0,
1503 // s_ is allowed to be of floating type.
1504 unsigned G3_SERIAL::serial = function::register_new(function_options("G", 3).
1505 evalf_func(G3_evalf).
1509 // derivative_func(G3_deriv).
1510 // print_func<print_latex>(G3_print_latex).
1513 //////////////////////////////////////////////////////////////////////
1515 // Classical polylogarithm and multiple polylogarithm Li(m,x)
1519 //////////////////////////////////////////////////////////////////////
1522 static ex Li_evalf(const ex& m_, const ex& x_)
1524 // classical polylogs
1525 if (m_.info(info_flags::posint)) {
1526 if (x_.info(info_flags::numeric)) {
1527 int m__ = ex_to<numeric>(m_).to_int();
1528 const cln::cl_N x__ = ex_to<numeric>(x_).to_cl_N();
1529 const cln::cl_N result = Lin_numeric(m__, x__);
1530 return numeric(result);
1532 // try to numerically evaluate second argument
1533 ex x_val = x_.evalf();
1534 if (x_val.info(info_flags::numeric)) {
1535 int m__ = ex_to<numeric>(m_).to_int();
1536 const cln::cl_N x__ = ex_to<numeric>(x_val).to_cl_N();
1537 const cln::cl_N result = Lin_numeric(m__, x__);
1538 return numeric(result);
1542 // multiple polylogs
1543 if (is_a<lst>(m_) && is_a<lst>(x_)) {
1545 const lst& m = ex_to<lst>(m_);
1546 const lst& x = ex_to<lst>(x_);
1547 if (m.nops() != x.nops()) {
1548 return Li(m_,x_).hold();
1550 if (x.nops() == 0) {
1553 if ((m.op(0) == _ex1) && (x.op(0) == _ex1)) {
1554 return Li(m_,x_).hold();
1557 for (auto itm = m.begin(), itx = x.begin(); itm != m.end(); ++itm, ++itx) {
1558 if (!(*itm).info(info_flags::posint)) {
1559 return Li(m_, x_).hold();
1561 if (!(*itx).info(info_flags::numeric)) {
1562 return Li(m_, x_).hold();
1569 return mLi_numeric(m, x);
1572 return Li(m_,x_).hold();
1576 static ex Li_eval(const ex& m_, const ex& x_)
1578 if (is_a<lst>(m_)) {
1579 if (is_a<lst>(x_)) {
1580 // multiple polylogs
1581 const lst& m = ex_to<lst>(m_);
1582 const lst& x = ex_to<lst>(x_);
1583 if (m.nops() != x.nops()) {
1584 return Li(m_,x_).hold();
1586 if (x.nops() == 0) {
1590 bool is_zeta = true;
1591 bool do_evalf = true;
1592 bool crational = true;
1593 for (auto itm = m.begin(), itx = x.begin(); itm != m.end(); ++itm, ++itx) {
1594 if (!(*itm).info(info_flags::posint)) {
1595 return Li(m_,x_).hold();
1597 if ((*itx != _ex1) && (*itx != _ex_1)) {
1598 if (itx != x.begin()) {
1606 if (!(*itx).info(info_flags::numeric)) {
1609 if (!(*itx).info(info_flags::crational)) {
1615 for (const auto & itx : x) {
1616 GINAC_ASSERT((itx == _ex1) || (itx == _ex_1));
1617 // XXX: 1 + 0.0*I is considered equal to 1. However
1618 // the former is a not automatically converted
1619 // to a real number. Do the conversion explicitly
1620 // to avoid the "numeric::operator>(): complex inequality"
1621 // exception (and similar problems).
1622 newx.append(itx != _ex_1 ? _ex1 : _ex_1);
1624 return zeta(m_, newx);
1628 lst newm = convert_parameter_Li_to_H(m, x, prefactor);
1629 return prefactor * H(newm, x[0]);
1631 if (do_evalf && !crational) {
1632 return mLi_numeric(m,x);
1635 return Li(m_, x_).hold();
1636 } else if (is_a<lst>(x_)) {
1637 return Li(m_, x_).hold();
1640 // classical polylogs
1648 return (pow(2,1-m_)-1) * zeta(m_);
1654 if (x_.is_equal(I)) {
1655 return power(Pi,_ex2)/_ex_48 + Catalan*I;
1657 if (x_.is_equal(-I)) {
1658 return power(Pi,_ex2)/_ex_48 - Catalan*I;
1661 if (m_.info(info_flags::posint) && x_.info(info_flags::numeric) && !x_.info(info_flags::crational)) {
1662 int m__ = ex_to<numeric>(m_).to_int();
1663 const cln::cl_N x__ = ex_to<numeric>(x_).to_cl_N();
1664 const cln::cl_N result = Lin_numeric(m__, x__);
1665 return numeric(result);
1668 return Li(m_, x_).hold();
1672 static ex Li_series(const ex& m, const ex& x, const relational& rel, int order, unsigned options)
1674 if (is_a<lst>(m) || is_a<lst>(x)) {
1676 epvector seq { expair(Li(m, x), 0) };
1677 return pseries(rel, std::move(seq));
1680 // classical polylog
1681 const ex x_pt = x.subs(rel, subs_options::no_pattern);
1682 if (m.info(info_flags::numeric) && x_pt.info(info_flags::numeric)) {
1683 // First special case: x==0 (derivatives have poles)
1684 if (x_pt.is_zero()) {
1687 // manually construct the primitive expansion
1688 for (int i=1; i<order; ++i)
1689 ser += pow(s,i) / pow(numeric(i), m);
1690 // substitute the argument's series expansion
1691 ser = ser.subs(s==x.series(rel, order), subs_options::no_pattern);
1692 // maybe that was terminating, so add a proper order term
1693 epvector nseq { expair(Order(_ex1), order) };
1694 ser += pseries(rel, std::move(nseq));
1695 // reexpanding it will collapse the series again
1696 return ser.series(rel, order);
1698 // TODO special cases: x==1 (branch point) and x real, >=1 (branch cut)
1699 throw std::runtime_error("Li_series: don't know how to do the series expansion at this point!");
1701 // all other cases should be safe, by now:
1702 throw do_taylor(); // caught by function::series()
1706 static ex Li_deriv(const ex& m_, const ex& x_, unsigned deriv_param)
1708 GINAC_ASSERT(deriv_param < 2);
1709 if (deriv_param == 0) {
1712 if (m_.nops() > 1) {
1713 throw std::runtime_error("don't know how to derivate multiple polylogarithm!");
1716 if (is_a<lst>(m_)) {
1722 if (is_a<lst>(x_)) {
1728 return Li(m-1, x) / x;
1735 static void Li_print_latex(const ex& m_, const ex& x_, const print_context& c)
1738 if (is_a<lst>(m_)) {
1744 if (is_a<lst>(x_)) {
1749 c.s << "\\mathrm{Li}_{";
1750 auto itm = m.begin();
1753 for (; itm != m.end(); itm++) {
1758 auto itx = x.begin();
1761 for (; itx != x.end(); itx++) {
1769 REGISTER_FUNCTION(Li,
1770 evalf_func(Li_evalf).
1772 series_func(Li_series).
1773 derivative_func(Li_deriv).
1774 print_func<print_latex>(Li_print_latex).
1775 do_not_evalf_params());
1778 //////////////////////////////////////////////////////////////////////
1780 // Nielsen's generalized polylogarithm S(n,p,x)
1784 //////////////////////////////////////////////////////////////////////
1787 // anonymous namespace for helper functions
1791 // lookup table for special Euler-Zagier-Sums (used for S_n,p(x))
1793 std::vector<std::vector<cln::cl_N>> Yn;
1794 int ynsize = 0; // number of Yn[]
1795 int ynlength = 100; // initial length of all Yn[i]
1798 // This function calculates the Y_n. The Y_n are needed for the evaluation of S_{n,p}(x).
1799 // The Y_n are basically Euler-Zagier sums with all m_i=1. They are subsums in the Z-sum
1800 // representing S_{n,p}(x).
1801 // The first index in Y_n corresponds to the parameter p minus one, i.e. the depth of the
1802 // equivalent Z-sum.
1803 // The second index in Y_n corresponds to the running index of the outermost sum in the full Z-sum
1804 // representing S_{n,p}(x).
1805 // The calculation of Y_n uses the values from Y_{n-1}.
1806 void fill_Yn(int n, const cln::float_format_t& prec)
1808 const int initsize = ynlength;
1809 //const int initsize = initsize_Yn;
1810 cln::cl_N one = cln::cl_float(1, prec);
1813 std::vector<cln::cl_N> buf(initsize);
1814 auto it = buf.begin();
1815 auto itprev = Yn[n-1].begin();
1816 *it = (*itprev) / cln::cl_N(n+1) * one;
1819 // sums with an index smaller than the depth are zero and need not to be calculated.
1820 // calculation starts with depth, which is n+2)
1821 for (int i=n+2; i<=initsize+n; i++) {
1822 *it = *(it-1) + (*itprev) / cln::cl_N(i) * one;
1828 std::vector<cln::cl_N> buf(initsize);
1829 auto it = buf.begin();
1832 for (int i=2; i<=initsize; i++) {
1833 *it = *(it-1) + 1 / cln::cl_N(i) * one;
1842 // make Yn longer ...
1843 void make_Yn_longer(int newsize, const cln::float_format_t& prec)
1846 cln::cl_N one = cln::cl_float(1, prec);
1848 Yn[0].resize(newsize);
1849 auto it = Yn[0].begin();
1851 for (int i=ynlength+1; i<=newsize; i++) {
1852 *it = *(it-1) + 1 / cln::cl_N(i) * one;
1856 for (int n=1; n<ynsize; n++) {
1857 Yn[n].resize(newsize);
1858 auto it = Yn[n].begin();
1859 auto itprev = Yn[n-1].begin();
1862 for (int i=ynlength+n+1; i<=newsize+n; i++) {
1863 *it = *(it-1) + (*itprev) / cln::cl_N(i) * one;
1873 // helper function for S(n,p,x)
1875 cln::cl_N C(int n, int p)
1879 for (int k=0; k<p; k++) {
1880 for (int j=0; j<=(n+k-1)/2; j++) {
1884 result = result - 2 * cln::expt(cln::pi(),2*j) * S_num(n-2*j,p,1) / cln::factorial(2*j);
1887 result = result + 2 * cln::expt(cln::pi(),2*j) * S_num(n-2*j,p,1) / cln::factorial(2*j);
1894 result = result + cln::factorial(n+k-1)
1895 * cln::expt(cln::pi(),2*j) * S_num(n+k-2*j,p-k,1)
1896 / (cln::factorial(k) * cln::factorial(n-1) * cln::factorial(2*j));
1899 result = result - cln::factorial(n+k-1)
1900 * cln::expt(cln::pi(),2*j) * S_num(n+k-2*j,p-k,1)
1901 / (cln::factorial(k) * cln::factorial(n-1) * cln::factorial(2*j));
1906 result = result - cln::factorial(n+k-1) * cln::expt(cln::pi(),2*j) * S_num(n+k-2*j,p-k,1)
1907 / (cln::factorial(k) * cln::factorial(n-1) * cln::factorial(2*j));
1910 result = result + cln::factorial(n+k-1)
1911 * cln::expt(cln::pi(),2*j) * S_num(n+k-2*j,p-k,1)
1912 / (cln::factorial(k) * cln::factorial(n-1) * cln::factorial(2*j));
1920 if (((np)/2+n) & 1) {
1921 result = -result - cln::expt(cln::pi(),np) / (np * cln::factorial(n-1) * cln::factorial(p));
1924 result = -result + cln::expt(cln::pi(),np) / (np * cln::factorial(n-1) * cln::factorial(p));
1932 // helper function for S(n,p,x)
1933 // [Kol] remark to (9.1)
1934 cln::cl_N a_k(int k)
1943 for (int m=2; m<=k; m++) {
1944 result = result + cln::expt(cln::cl_N(-1),m) * cln::zeta(m) * a_k(k-m);
1951 // helper function for S(n,p,x)
1952 // [Kol] remark to (9.1)
1953 cln::cl_N b_k(int k)
1962 for (int m=2; m<=k; m++) {
1963 result = result + cln::expt(cln::cl_N(-1),m) * cln::zeta(m) * b_k(k-m);
1970 // helper function for S(n,p,x)
1971 cln::cl_N S_do_sum(int n, int p, const cln::cl_N& x, const cln::float_format_t& prec)
1973 static cln::float_format_t oldprec = cln::default_float_format;
1976 return Li_projection(n+1, x, prec);
1979 // precision has changed, we need to clear lookup table Yn
1980 if ( oldprec != prec ) {
1987 // check if precalculated values are sufficient
1989 for (int i=ynsize; i<p-1; i++) {
1994 // should be done otherwise
1995 cln::cl_F one = cln::cl_float(1, cln::float_format(Digits));
1996 cln::cl_N xf = x * one;
1997 //cln::cl_N xf = x * cln::cl_float(1, prec);
2001 cln::cl_N factor = cln::expt(xf, p);
2005 if (i-p >= ynlength) {
2007 make_Yn_longer(ynlength*2, prec);
2009 res = res + factor / cln::expt(cln::cl_I(i),n+1) * Yn[p-2][i-p]; // should we check it? or rely on magic number? ...
2010 //res = res + factor / cln::expt(cln::cl_I(i),n+1) * (*it); // should we check it? or rely on magic number? ...
2011 factor = factor * xf;
2013 } while (res != resbuf);
2019 // helper function for S(n,p,x)
2020 cln::cl_N S_projection(int n, int p, const cln::cl_N& x, const cln::float_format_t& prec)
2023 if (cln::abs(cln::realpart(x)) > cln::cl_F("0.5")) {
2025 cln::cl_N result = cln::expt(cln::cl_I(-1),p) * cln::expt(cln::log(x),n)
2026 * cln::expt(cln::log(1-x),p) / cln::factorial(n) / cln::factorial(p);
2028 for (int s=0; s<n; s++) {
2030 for (int r=0; r<p; r++) {
2031 res2 = res2 + cln::expt(cln::cl_I(-1),r) * cln::expt(cln::log(1-x),r)
2032 * S_do_sum(p-r,n-s,1-x,prec) / cln::factorial(r);
2034 result = result + cln::expt(cln::log(x),s) * (S_num(n-s,p,1) - res2) / cln::factorial(s);
2040 return S_do_sum(n, p, x, prec);
2044 // helper function for S(n,p,x)
2045 const cln::cl_N S_num(int n, int p, const cln::cl_N& x)
2049 // [Kol] (2.22) with (2.21)
2050 return cln::zeta(p+1);
2055 return cln::zeta(n+1);
2060 for (int nu=0; nu<n; nu++) {
2061 for (int rho=0; rho<=p; rho++) {
2062 result = result + b_k(n-nu-1) * b_k(p-rho) * a_k(nu+rho+1)
2063 * cln::factorial(nu+rho+1) / cln::factorial(rho) / cln::factorial(nu+1);
2066 result = result * cln::expt(cln::cl_I(-1),n+p-1);
2073 return -(1-cln::expt(cln::cl_I(2),-n)) * cln::zeta(n+1);
2075 // throw std::runtime_error("don't know how to evaluate this function!");
2078 // what is the desired float format?
2079 // first guess: default format
2080 cln::float_format_t prec = cln::default_float_format;
2081 const cln::cl_N value = x;
2082 // second guess: the argument's format
2083 if (!instanceof(realpart(value), cln::cl_RA_ring))
2084 prec = cln::float_format(cln::the<cln::cl_F>(cln::realpart(value)));
2085 else if (!instanceof(imagpart(value), cln::cl_RA_ring))
2086 prec = cln::float_format(cln::the<cln::cl_F>(cln::imagpart(value)));
2089 // the condition abs(1-value)>1 avoids an infinite recursion in the region abs(value)<=1 && abs(value)>0.95 && abs(1-value)<=1 && abs(1-value)>0.95
2090 // we don't care here about abs(value)<1 && real(value)>0.5, this will be taken care of in S_projection
2091 if ((cln::realpart(value) < -0.5) || (n == 0) || ((cln::abs(value) <= 1) && (cln::abs(value) > 0.95) && (cln::abs(1-value) > 1) )) {
2093 cln::cl_N result = cln::expt(cln::cl_I(-1),p) * cln::expt(cln::log(value),n)
2094 * cln::expt(cln::log(1-value),p) / cln::factorial(n) / cln::factorial(p);
2096 for (int s=0; s<n; s++) {
2098 for (int r=0; r<p; r++) {
2099 res2 = res2 + cln::expt(cln::cl_I(-1),r) * cln::expt(cln::log(1-value),r)
2100 * S_num(p-r,n-s,1-value) / cln::factorial(r);
2102 result = result + cln::expt(cln::log(value),s) * (S_num(n-s,p,1) - res2) / cln::factorial(s);
2109 if (cln::abs(value) > 1) {
2113 for (int s=0; s<p; s++) {
2114 for (int r=0; r<=s; r++) {
2115 result = result + cln::expt(cln::cl_I(-1),s) * cln::expt(cln::log(-value),r) * cln::factorial(n+s-r-1)
2116 / cln::factorial(r) / cln::factorial(s-r) / cln::factorial(n-1)
2117 * S_num(n+s-r,p-s,cln::recip(value));
2120 result = result * cln::expt(cln::cl_I(-1),n);
2123 for (int r=0; r<n; r++) {
2124 res2 = res2 + cln::expt(cln::log(-value),r) * C(n-r,p) / cln::factorial(r);
2126 res2 = res2 + cln::expt(cln::log(-value),n+p) / cln::factorial(n+p);
2128 result = result + cln::expt(cln::cl_I(-1),p) * res2;
2133 if ((cln::abs(value) > 0.95) && (cln::abs(value-9.53) < 9.47)) {
2136 for (int s=0; s<p-1; s++)
2139 ex res = H(m,numeric(value)).evalf();
2140 return ex_to<numeric>(res).to_cl_N();
2143 return S_projection(n, p, value, prec);
2148 } // end of anonymous namespace
2151 //////////////////////////////////////////////////////////////////////
2153 // Nielsen's generalized polylogarithm S(n,p,x)
2157 //////////////////////////////////////////////////////////////////////
2160 static ex S_evalf(const ex& n, const ex& p, const ex& x)
2162 if (n.info(info_flags::posint) && p.info(info_flags::posint)) {
2163 const int n_ = ex_to<numeric>(n).to_int();
2164 const int p_ = ex_to<numeric>(p).to_int();
2165 if (is_a<numeric>(x)) {
2166 const cln::cl_N x_ = ex_to<numeric>(x).to_cl_N();
2167 const cln::cl_N result = S_num(n_, p_, x_);
2168 return numeric(result);
2170 ex x_val = x.evalf();
2171 if (is_a<numeric>(x_val)) {
2172 const cln::cl_N x_val_ = ex_to<numeric>(x_val).to_cl_N();
2173 const cln::cl_N result = S_num(n_, p_, x_val_);
2174 return numeric(result);
2178 return S(n, p, x).hold();
2182 static ex S_eval(const ex& n, const ex& p, const ex& x)
2184 if (n.info(info_flags::posint) && p.info(info_flags::posint)) {
2190 for (int i=ex_to<numeric>(p).to_int()-1; i>0; i--) {
2198 if (x.info(info_flags::numeric) && (!x.info(info_flags::crational))) {
2199 int n_ = ex_to<numeric>(n).to_int();
2200 int p_ = ex_to<numeric>(p).to_int();
2201 const cln::cl_N x_ = ex_to<numeric>(x).to_cl_N();
2202 const cln::cl_N result = S_num(n_, p_, x_);
2203 return numeric(result);
2208 return pow(-log(1-x), p) / factorial(p);
2210 return S(n, p, x).hold();
2214 static ex S_series(const ex& n, const ex& p, const ex& x, const relational& rel, int order, unsigned options)
2217 return Li(n+1, x).series(rel, order, options);
2220 const ex x_pt = x.subs(rel, subs_options::no_pattern);
2221 if (n.info(info_flags::posint) && p.info(info_flags::posint) && x_pt.info(info_flags::numeric)) {
2222 // First special case: x==0 (derivatives have poles)
2223 if (x_pt.is_zero()) {
2226 // manually construct the primitive expansion
2227 // subsum = Euler-Zagier-Sum is needed
2228 // dirty hack (slow ...) calculation of subsum:
2229 std::vector<ex> presubsum, subsum;
2230 subsum.push_back(0);
2231 for (int i=1; i<order-1; ++i) {
2232 subsum.push_back(subsum[i-1] + numeric(1, i));
2234 for (int depth=2; depth<p; ++depth) {
2236 for (int i=1; i<order-1; ++i) {
2237 subsum[i] = subsum[i-1] + numeric(1, i) * presubsum[i-1];
2241 for (int i=1; i<order; ++i) {
2242 ser += pow(s,i) / pow(numeric(i), n+1) * subsum[i-1];
2244 // substitute the argument's series expansion
2245 ser = ser.subs(s==x.series(rel, order), subs_options::no_pattern);
2246 // maybe that was terminating, so add a proper order term
2247 epvector nseq { expair(Order(_ex1), order) };
2248 ser += pseries(rel, std::move(nseq));
2249 // reexpanding it will collapse the series again
2250 return ser.series(rel, order);
2252 // TODO special cases: x==1 (branch point) and x real, >=1 (branch cut)
2253 throw std::runtime_error("S_series: don't know how to do the series expansion at this point!");
2255 // all other cases should be safe, by now:
2256 throw do_taylor(); // caught by function::series()
2260 static ex S_deriv(const ex& n, const ex& p, const ex& x, unsigned deriv_param)
2262 GINAC_ASSERT(deriv_param < 3);
2263 if (deriv_param < 2) {
2267 return S(n-1, p, x) / x;
2269 return S(n, p-1, x) / (1-x);
2274 static void S_print_latex(const ex& n, const ex& p, const ex& x, const print_context& c)
2276 c.s << "\\mathrm{S}_{";
2286 REGISTER_FUNCTION(S,
2287 evalf_func(S_evalf).
2289 series_func(S_series).
2290 derivative_func(S_deriv).
2291 print_func<print_latex>(S_print_latex).
2292 do_not_evalf_params());
2295 //////////////////////////////////////////////////////////////////////
2297 // Harmonic polylogarithm H(m,x)
2301 //////////////////////////////////////////////////////////////////////
2304 // anonymous namespace for helper functions
2308 // regulates the pole (used by 1/x-transformation)
2309 symbol H_polesign("IMSIGN");
2312 // convert parameters from H to Li representation
2313 // parameters are expected to be in expanded form, i.e. only 0, 1 and -1
2314 // returns true if some parameters are negative
2315 bool convert_parameter_H_to_Li(const lst& l, lst& m, lst& s, ex& pf)
2317 // expand parameter list
2319 for (const auto & it : l) {
2321 for (ex count=it-1; count > 0; count--) {
2325 } else if (it < -1) {
2326 for (ex count=it+1; count < 0; count++) {
2337 bool has_negative_parameters = false;
2339 for (const auto & it : mexp) {
2345 m.append((it+acc-1) * signum);
2347 m.append((it-acc+1) * signum);
2353 has_negative_parameters = true;
2356 if (has_negative_parameters) {
2357 for (std::size_t i=0; i<m.nops(); i++) {
2359 m.let_op(i) = -m.op(i);
2367 return has_negative_parameters;
2371 // recursivly transforms H to corresponding multiple polylogarithms
2372 struct map_trafo_H_convert_to_Li : public map_function
2374 ex operator()(const ex& e) override
2376 if (is_a<add>(e) || is_a<mul>(e)) {
2377 return e.map(*this);
2379 if (is_a<function>(e)) {
2380 std::string name = ex_to<function>(e).get_name();
2383 if (is_a<lst>(e.op(0))) {
2384 parameter = ex_to<lst>(e.op(0));
2386 parameter = lst{e.op(0)};
2393 if (convert_parameter_H_to_Li(parameter, m, s, pf)) {
2394 s.let_op(0) = s.op(0) * arg;
2395 return pf * Li(m, s).hold();
2397 for (std::size_t i=0; i<m.nops(); i++) {
2400 s.let_op(0) = s.op(0) * arg;
2401 return Li(m, s).hold();
2410 // recursivly transforms H to corresponding zetas
2411 struct map_trafo_H_convert_to_zeta : public map_function
2413 ex operator()(const ex& e) override
2415 if (is_a<add>(e) || is_a<mul>(e)) {
2416 return e.map(*this);
2418 if (is_a<function>(e)) {
2419 std::string name = ex_to<function>(e).get_name();
2422 if (is_a<lst>(e.op(0))) {
2423 parameter = ex_to<lst>(e.op(0));
2425 parameter = lst{e.op(0)};
2431 if (convert_parameter_H_to_Li(parameter, m, s, pf)) {
2432 return pf * zeta(m, s);
2443 // remove trailing zeros from H-parameters
2444 struct map_trafo_H_reduce_trailing_zeros : public map_function
2446 ex operator()(const ex& e) override
2448 if (is_a<add>(e) || is_a<mul>(e)) {
2449 return e.map(*this);
2451 if (is_a<function>(e)) {
2452 std::string name = ex_to<function>(e).get_name();
2455 if (is_a<lst>(e.op(0))) {
2456 parameter = ex_to<lst>(e.op(0));
2458 parameter = lst{e.op(0)};
2461 if (parameter.op(parameter.nops()-1) == 0) {
2464 if (parameter.nops() == 1) {
2469 auto it = parameter.begin();
2470 while ((it != parameter.end()) && (*it == 0)) {
2473 if (it == parameter.end()) {
2474 return pow(log(arg),parameter.nops()) / factorial(parameter.nops());
2478 parameter.remove_last();
2479 std::size_t lastentry = parameter.nops();
2480 while ((lastentry > 0) && (parameter[lastentry-1] == 0)) {
2485 ex result = log(arg) * H(parameter,arg).hold();
2487 for (ex i=0; i<lastentry; i++) {
2488 if (parameter[i] > 0) {
2490 result -= (acc + parameter[i]-1) * H(parameter, arg).hold();
2493 } else if (parameter[i] < 0) {
2495 result -= (acc + abs(parameter[i]+1)) * H(parameter, arg).hold();
2503 if (lastentry < parameter.nops()) {
2504 result = result / (parameter.nops()-lastentry+1);
2505 return result.map(*this);
2517 // returns an expression with zeta functions corresponding to the parameter list for H
2518 ex convert_H_to_zeta(const lst& m)
2520 symbol xtemp("xtemp");
2521 map_trafo_H_reduce_trailing_zeros filter;
2522 map_trafo_H_convert_to_zeta filter2;
2523 return filter2(filter(H(m, xtemp).hold())).subs(xtemp == 1);
2527 // convert signs form Li to H representation
2528 lst convert_parameter_Li_to_H(const lst& m, const lst& x, ex& pf)
2531 auto itm = m.begin();
2532 auto itx = ++x.begin();
2537 while (itx != x.end()) {
2538 GINAC_ASSERT((*itx == _ex1) || (*itx == _ex_1));
2539 // XXX: 1 + 0.0*I is considered equal to 1. However the former
2540 // is not automatically converted to a real number.
2541 // Do the conversion explicitly to avoid the
2542 // "numeric::operator>(): complex inequality" exception.
2543 signum *= (*itx != _ex_1) ? 1 : -1;
2545 res.append((*itm) * signum);
2553 // multiplies an one-dimensional H with another H
2555 ex trafo_H_mult(const ex& h1, const ex& h2)
2560 ex h1nops = h1.op(0).nops();
2561 ex h2nops = h2.op(0).nops();
2563 hshort = h2.op(0).op(0);
2564 hlong = ex_to<lst>(h1.op(0));
2566 hshort = h1.op(0).op(0);
2568 hlong = ex_to<lst>(h2.op(0));
2570 hlong = lst{h2.op(0).op(0)};
2573 for (std::size_t i=0; i<=hlong.nops(); i++) {
2577 newparameter.append(hlong[j]);
2579 newparameter.append(hshort);
2580 for (; j<hlong.nops(); j++) {
2581 newparameter.append(hlong[j]);
2583 res += H(newparameter, h1.op(1)).hold();
2589 // applies trafo_H_mult recursively on expressions
2590 struct map_trafo_H_mult : public map_function
2592 ex operator()(const ex& e) override
2595 return e.map(*this);
2603 for (std::size_t pos=0; pos<e.nops(); pos++) {
2604 if (is_a<power>(e.op(pos)) && is_a<function>(e.op(pos).op(0))) {
2605 std::string name = ex_to<function>(e.op(pos).op(0)).get_name();
2607 for (ex i=0; i<e.op(pos).op(1); i++) {
2608 Hlst.append(e.op(pos).op(0));
2612 } else if (is_a<function>(e.op(pos))) {
2613 std::string name = ex_to<function>(e.op(pos)).get_name();
2615 if (e.op(pos).op(0).nops() > 1) {
2618 Hlst.append(e.op(pos));
2623 result *= e.op(pos);
2626 if (Hlst.nops() > 0) {
2627 firstH = Hlst[Hlst.nops()-1];
2634 if (Hlst.nops() > 0) {
2635 ex buffer = trafo_H_mult(firstH, Hlst.op(0));
2637 for (std::size_t i=1; i<Hlst.nops(); i++) {
2638 result *= Hlst.op(i);
2640 result = result.expand();
2641 map_trafo_H_mult recursion;
2642 return recursion(result);
2653 // do integration [ReV] (55)
2654 // put parameter 0 in front of existing parameters
2655 ex trafo_H_1tx_prepend_zero(const ex& e, const ex& arg)
2659 if (is_a<function>(e)) {
2660 name = ex_to<function>(e).get_name();
2665 for (std::size_t i=0; i<e.nops(); i++) {
2666 if (is_a<function>(e.op(i))) {
2667 std::string name = ex_to<function>(e.op(i)).get_name();
2675 lst newparameter = ex_to<lst>(h.op(0));
2676 newparameter.prepend(0);
2677 ex addzeta = convert_H_to_zeta(newparameter);
2678 return e.subs(h == (addzeta-H(newparameter, h.op(1)).hold())).expand();
2680 return e * (-H(lst{ex(0)},1/arg).hold());
2685 // do integration [ReV] (49)
2686 // put parameter 1 in front of existing parameters
2687 ex trafo_H_prepend_one(const ex& e, const ex& arg)
2691 if (is_a<function>(e)) {
2692 name = ex_to<function>(e).get_name();
2697 for (std::size_t i=0; i<e.nops(); i++) {
2698 if (is_a<function>(e.op(i))) {
2699 std::string name = ex_to<function>(e.op(i)).get_name();
2707 lst newparameter = ex_to<lst>(h.op(0));
2708 newparameter.prepend(1);
2709 return e.subs(h == H(newparameter, h.op(1)).hold());
2711 return e * H(lst{ex(1)},1-arg).hold();
2716 // do integration [ReV] (55)
2717 // put parameter -1 in front of existing parameters
2718 ex trafo_H_1tx_prepend_minusone(const ex& e, const ex& arg)
2722 if (is_a<function>(e)) {
2723 name = ex_to<function>(e).get_name();
2728 for (std::size_t i=0; i<e.nops(); i++) {
2729 if (is_a<function>(e.op(i))) {
2730 std::string name = ex_to<function>(e.op(i)).get_name();
2738 lst newparameter = ex_to<lst>(h.op(0));
2739 newparameter.prepend(-1);
2740 ex addzeta = convert_H_to_zeta(newparameter);
2741 return e.subs(h == (addzeta-H(newparameter, h.op(1)).hold())).expand();
2743 ex addzeta = convert_H_to_zeta(lst{ex(-1)});
2744 return (e * (addzeta - H(lst{ex(-1)},1/arg).hold())).expand();
2749 // do integration [ReV] (55)
2750 // put parameter -1 in front of existing parameters
2751 ex trafo_H_1mxt1px_prepend_minusone(const ex& e, const ex& arg)
2755 if (is_a<function>(e)) {
2756 name = ex_to<function>(e).get_name();
2761 for (std::size_t i = 0; i < e.nops(); i++) {
2762 if (is_a<function>(e.op(i))) {
2763 std::string name = ex_to<function>(e.op(i)).get_name();
2771 lst newparameter = ex_to<lst>(h.op(0));
2772 newparameter.prepend(-1);
2773 return e.subs(h == H(newparameter, h.op(1)).hold()).expand();
2775 return (e * H(lst{ex(-1)},(1-arg)/(1+arg)).hold()).expand();
2780 // do integration [ReV] (55)
2781 // put parameter 1 in front of existing parameters
2782 ex trafo_H_1mxt1px_prepend_one(const ex& e, const ex& arg)
2786 if (is_a<function>(e)) {
2787 name = ex_to<function>(e).get_name();
2792 for (std::size_t i = 0; i < e.nops(); i++) {
2793 if (is_a<function>(e.op(i))) {
2794 std::string name = ex_to<function>(e.op(i)).get_name();
2802 lst newparameter = ex_to<lst>(h.op(0));
2803 newparameter.prepend(1);
2804 return e.subs(h == H(newparameter, h.op(1)).hold()).expand();
2806 return (e * H(lst{ex(1)},(1-arg)/(1+arg)).hold()).expand();
2811 // do x -> 1-x transformation
2812 struct map_trafo_H_1mx : public map_function
2814 ex operator()(const ex& e) override
2816 if (is_a<add>(e) || is_a<mul>(e)) {
2817 return e.map(*this);
2820 if (is_a<function>(e)) {
2821 std::string name = ex_to<function>(e).get_name();
2824 lst parameter = ex_to<lst>(e.op(0));
2827 // special cases if all parameters are either 0, 1 or -1
2828 bool allthesame = true;
2829 if (parameter.op(0) == 0) {
2830 for (std::size_t i = 1; i < parameter.nops(); i++) {
2831 if (parameter.op(i) != 0) {
2838 for (int i=parameter.nops(); i>0; i--) {
2839 newparameter.append(1);
2841 return pow(-1, parameter.nops()) * H(newparameter, 1-arg).hold();
2843 } else if (parameter.op(0) == -1) {
2844 throw std::runtime_error("map_trafo_H_1mx: cannot handle weights equal -1!");
2846 for (std::size_t i = 1; i < parameter.nops(); i++) {
2847 if (parameter.op(i) != 1) {
2854 for (int i=parameter.nops(); i>0; i--) {
2855 newparameter.append(0);
2857 return pow(-1, parameter.nops()) * H(newparameter, 1-arg).hold();
2861 lst newparameter = parameter;
2862 newparameter.remove_first();
2864 if (parameter.op(0) == 0) {
2867 ex res = convert_H_to_zeta(parameter);
2868 //ex res = convert_from_RV(parameter, 1).subs(H(wild(1),wild(2))==zeta(wild(1)));
2869 map_trafo_H_1mx recursion;
2870 ex buffer = recursion(H(newparameter, arg).hold());
2871 if (is_a<add>(buffer)) {
2872 for (std::size_t i = 0; i < buffer.nops(); i++) {
2873 res -= trafo_H_prepend_one(buffer.op(i), arg);
2876 res -= trafo_H_prepend_one(buffer, arg);
2883 map_trafo_H_1mx recursion;
2884 map_trafo_H_mult unify;
2885 ex res = H(lst{ex(1)}, arg).hold() * H(newparameter, arg).hold();
2886 std::size_t firstzero = 0;
2887 while (parameter.op(firstzero) == 1) {
2890 for (std::size_t i = firstzero-1; i < parameter.nops()-1; i++) {
2894 newparameter.append(parameter[j+1]);
2896 newparameter.append(1);
2897 for (; j<parameter.nops()-1; j++) {
2898 newparameter.append(parameter[j+1]);
2900 res -= H(newparameter, arg).hold();
2902 res = recursion(res).expand() / firstzero;
2912 // do x -> 1/x transformation
2913 struct map_trafo_H_1overx : public map_function
2915 ex operator()(const ex& e) override
2917 if (is_a<add>(e) || is_a<mul>(e)) {
2918 return e.map(*this);
2921 if (is_a<function>(e)) {
2922 std::string name = ex_to<function>(e).get_name();
2925 lst parameter = ex_to<lst>(e.op(0));
2928 // special cases if all parameters are either 0, 1 or -1
2929 bool allthesame = true;
2930 if (parameter.op(0) == 0) {
2931 for (std::size_t i = 1; i < parameter.nops(); i++) {
2932 if (parameter.op(i) != 0) {
2938 return pow(-1, parameter.nops()) * H(parameter, 1/arg).hold();
2940 } else if (parameter.op(0) == -1) {
2941 for (std::size_t i = 1; i < parameter.nops(); i++) {
2942 if (parameter.op(i) != -1) {
2948 map_trafo_H_mult unify;
2949 return unify((pow(H(lst{ex(-1)},1/arg).hold() - H(lst{ex(0)},1/arg).hold(), parameter.nops())
2950 / factorial(parameter.nops())).expand());
2953 for (std::size_t i = 1; i < parameter.nops(); i++) {
2954 if (parameter.op(i) != 1) {
2960 map_trafo_H_mult unify;
2961 return unify((pow(H(lst{ex(1)},1/arg).hold() + H(lst{ex(0)},1/arg).hold() + H_polesign, parameter.nops())
2962 / factorial(parameter.nops())).expand());
2966 lst newparameter = parameter;
2967 newparameter.remove_first();
2969 if (parameter.op(0) == 0) {
2972 ex res = convert_H_to_zeta(parameter);
2973 map_trafo_H_1overx recursion;
2974 ex buffer = recursion(H(newparameter, arg).hold());
2975 if (is_a<add>(buffer)) {
2976 for (std::size_t i = 0; i < buffer.nops(); i++) {
2977 res += trafo_H_1tx_prepend_zero(buffer.op(i), arg);
2980 res += trafo_H_1tx_prepend_zero(buffer, arg);
2984 } else if (parameter.op(0) == -1) {
2986 // leading negative one
2987 ex res = convert_H_to_zeta(parameter);
2988 map_trafo_H_1overx recursion;
2989 ex buffer = recursion(H(newparameter, arg).hold());
2990 if (is_a<add>(buffer)) {
2991 for (std::size_t i = 0; i < buffer.nops(); i++) {
2992 res += trafo_H_1tx_prepend_zero(buffer.op(i), arg) - trafo_H_1tx_prepend_minusone(buffer.op(i), arg);
2995 res += trafo_H_1tx_prepend_zero(buffer, arg) - trafo_H_1tx_prepend_minusone(buffer, arg);
3002 map_trafo_H_1overx recursion;
3003 map_trafo_H_mult unify;
3004 ex res = H(lst{ex(1)}, arg).hold() * H(newparameter, arg).hold();
3005 std::size_t firstzero = 0;
3006 while (parameter.op(firstzero) == 1) {
3009 for (std::size_t i = firstzero-1; i < parameter.nops() - 1; i++) {
3013 newparameter.append(parameter[j+1]);
3015 newparameter.append(1);
3016 for (; j<parameter.nops()-1; j++) {
3017 newparameter.append(parameter[j+1]);
3019 res -= H(newparameter, arg).hold();
3021 res = recursion(res).expand() / firstzero;
3033 // do x -> (1-x)/(1+x) transformation
3034 struct map_trafo_H_1mxt1px : public map_function
3036 ex operator()(const ex& e) override
3038 if (is_a<add>(e) || is_a<mul>(e)) {
3039 return e.map(*this);
3042 if (is_a<function>(e)) {
3043 std::string name = ex_to<function>(e).get_name();
3046 lst parameter = ex_to<lst>(e.op(0));
3049 // special cases if all parameters are either 0, 1 or -1
3050 bool allthesame = true;
3051 if (parameter.op(0) == 0) {
3052 for (std::size_t i = 1; i < parameter.nops(); i++) {
3053 if (parameter.op(i) != 0) {
3059 map_trafo_H_mult unify;
3060 return unify((pow(-H(lst{ex(1)},(1-arg)/(1+arg)).hold() - H(lst{ex(-1)},(1-arg)/(1+arg)).hold(), parameter.nops())
3061 / factorial(parameter.nops())).expand());
3063 } else if (parameter.op(0) == -1) {
3064 for (std::size_t i = 1; i < parameter.nops(); i++) {
3065 if (parameter.op(i) != -1) {
3071 map_trafo_H_mult unify;
3072 return unify((pow(log(2) - H(lst{ex(-1)},(1-arg)/(1+arg)).hold(), parameter.nops())
3073 / factorial(parameter.nops())).expand());
3076 for (std::size_t i = 1; i < parameter.nops(); i++) {
3077 if (parameter.op(i) != 1) {
3083 map_trafo_H_mult unify;
3084 return unify((pow(-log(2) - H(lst{ex(0)},(1-arg)/(1+arg)).hold() + H(lst{ex(-1)},(1-arg)/(1+arg)).hold(), parameter.nops())
3085 / factorial(parameter.nops())).expand());
3089 lst newparameter = parameter;
3090 newparameter.remove_first();
3092 if (parameter.op(0) == 0) {
3095 ex res = convert_H_to_zeta(parameter);
3096 map_trafo_H_1mxt1px recursion;
3097 ex buffer = recursion(H(newparameter, arg).hold());
3098 if (is_a<add>(buffer)) {
3099 for (std::size_t i = 0; i < buffer.nops(); i++) {
3100 res -= trafo_H_1mxt1px_prepend_one(buffer.op(i), arg) + trafo_H_1mxt1px_prepend_minusone(buffer.op(i), arg);
3103 res -= trafo_H_1mxt1px_prepend_one(buffer, arg) + trafo_H_1mxt1px_prepend_minusone(buffer, arg);
3107 } else if (parameter.op(0) == -1) {
3109 // leading negative one
3110 ex res = convert_H_to_zeta(parameter);
3111 map_trafo_H_1mxt1px recursion;
3112 ex buffer = recursion(H(newparameter, arg).hold());
3113 if (is_a<add>(buffer)) {
3114 for (std::size_t i = 0; i < buffer.nops(); i++) {
3115 res -= trafo_H_1mxt1px_prepend_minusone(buffer.op(i), arg);
3118 res -= trafo_H_1mxt1px_prepend_minusone(buffer, arg);
3125 map_trafo_H_1mxt1px recursion;
3126 map_trafo_H_mult unify;
3127 ex res = H(lst{ex(1)}, arg).hold() * H(newparameter, arg).hold();
3128 std::size_t firstzero = 0;
3129 while (parameter.op(firstzero) == 1) {
3132 for (std::size_t i = firstzero - 1; i < parameter.nops() - 1; i++) {
3136 newparameter.append(parameter[j+1]);
3138 newparameter.append(1);
3139 for (; j<parameter.nops()-1; j++) {
3140 newparameter.append(parameter[j+1]);
3142 res -= H(newparameter, arg).hold();
3144 res = recursion(res).expand() / firstzero;
3156 // do the actual summation.
3157 cln::cl_N H_do_sum(const std::vector<int>& m, const cln::cl_N& x)
3159 const int j = m.size();
3161 std::vector<cln::cl_N> t(j);
3163 cln::cl_F one = cln::cl_float(1, cln::float_format(Digits));
3164 cln::cl_N factor = cln::expt(x, j) * one;
3170 t[j-1] = t[j-1] + 1 / cln::expt(cln::cl_I(q),m[j-1]);
3171 for (int k=j-2; k>=1; k--) {
3172 t[k] = t[k] + t[k+1] / cln::expt(cln::cl_I(q+j-1-k), m[k]);
3174 t[0] = t[0] + t[1] * factor / cln::expt(cln::cl_I(q+j-1), m[0]);
3175 factor = factor * x;
3176 } while (t[0] != t0buf);
3182 } // end of anonymous namespace
3185 //////////////////////////////////////////////////////////////////////
3187 // Harmonic polylogarithm H(m,x)
3191 //////////////////////////////////////////////////////////////////////
3194 static ex H_evalf(const ex& x1, const ex& x2)
3196 if (is_a<lst>(x1)) {
3199 if (is_a<numeric>(x2)) {
3200 x = ex_to<numeric>(x2).to_cl_N();
3202 ex x2_val = x2.evalf();
3203 if (is_a<numeric>(x2_val)) {
3204 x = ex_to<numeric>(x2_val).to_cl_N();
3208 for (std::size_t i = 0; i < x1.nops(); i++) {
3209 if (!x1.op(i).info(info_flags::integer)) {
3210 return H(x1, x2).hold();
3213 if (x1.nops() < 1) {
3214 return H(x1, x2).hold();
3217 const lst& morg = ex_to<lst>(x1);
3218 // remove trailing zeros ...
3219 if (*(--morg.end()) == 0) {
3220 symbol xtemp("xtemp");
3221 map_trafo_H_reduce_trailing_zeros filter;
3222 return filter(H(x1, xtemp).hold()).subs(xtemp==x2).evalf();
3224 // ... and expand parameter notation
3225 bool has_minus_one = false;
3227 for (const auto & it : morg) {
3229 for (ex count=it-1; count > 0; count--) {
3233 } else if (it <= -1) {
3234 for (ex count=it+1; count < 0; count++) {
3238 has_minus_one = true;
3245 if (cln::abs(x) < 0.95) {
3249 if (convert_parameter_H_to_Li(m, m_lst, s_lst, pf)) {
3250 // negative parameters -> s_lst is filled
3251 std::vector<int> m_int;
3252 std::vector<cln::cl_N> x_cln;
3253 for (auto it_int = m_lst.begin(), it_cln = s_lst.begin();
3254 it_int != m_lst.end(); it_int++, it_cln++) {
3255 m_int.push_back(ex_to<numeric>(*it_int).to_int());
3256 x_cln.push_back(ex_to<numeric>(*it_cln).to_cl_N());
3258 x_cln.front() = x_cln.front() * x;
3259 return pf * numeric(multipleLi_do_sum(m_int, x_cln));
3261 // only positive parameters
3263 if (m_lst.nops() == 1) {
3264 return Li(m_lst.op(0), x2).evalf();
3266 std::vector<int> m_int;
3267 for (const auto & it : m_lst) {
3268 m_int.push_back(ex_to<numeric>(it).to_int());
3270 return numeric(H_do_sum(m_int, x));
3274 symbol xtemp("xtemp");
3277 // ensure that the realpart of the argument is positive
3278 if (cln::realpart(x) < 0) {
3280 for (std::size_t i = 0; i < m.nops(); i++) {
3282 m.let_op(i) = -m.op(i);
3289 if (cln::abs(x) >= 2.0) {
3290 map_trafo_H_1overx trafo;
3291 res *= trafo(H(m, xtemp).hold());
3292 if (cln::imagpart(x) <= 0) {
3293 res = res.subs(H_polesign == -I*Pi);
3295 res = res.subs(H_polesign == I*Pi);
3297 return res.subs(xtemp == numeric(x)).evalf();
3300 // check transformations for 0.95 <= |x| < 2.0
3302 // |(1-x)/(1+x)| < 0.9 -> circular area with center=9.53+0i and radius=9.47
3303 if (cln::abs(x-9.53) <= 9.47) {
3305 map_trafo_H_1mxt1px trafo;
3306 res *= trafo(H(m, xtemp).hold());
3309 if (has_minus_one) {
3310 map_trafo_H_convert_to_Li filter;
3311 return filter(H(m, numeric(x)).hold()).evalf();
3313 map_trafo_H_1mx trafo;
3314 res *= trafo(H(m, xtemp).hold());
3317 return res.subs(xtemp == numeric(x)).evalf();
3320 return H(x1,x2).hold();
3324 static ex H_eval(const ex& m_, const ex& x)
3327 if (is_a<lst>(m_)) {
3332 if (m.nops() == 0) {
3340 if (*m.begin() > _ex1) {
3346 } else if (*m.begin() < _ex_1) {
3352 } else if (*m.begin() == _ex0) {
3359 for (auto it = ++m.begin(); it != m.end(); it++) {
3360 if (it->info(info_flags::integer)) {
3371 } else if (*it < _ex_1) {
3391 } else if (step == 1) {
3403 // if some m_i is not an integer
3404 return H(m_, x).hold();
3407 if ((x == _ex1) && (*(--m.end()) != _ex0)) {
3408 return convert_H_to_zeta(m);
3414 return H(m_, x).hold();
3416 return pow(log(x), m.nops()) / factorial(m.nops());
3419 return pow(-pos1*log(1-pos1*x), m.nops()) / factorial(m.nops());
3421 } else if ((step == 1) && (pos1 == _ex0)){
3426 return pow(-1, p) * S(n, p, -x);
3432 if (x.info(info_flags::numeric) && (!x.info(info_flags::crational))) {
3433 return H(m_, x).evalf();
3435 return H(m_, x).hold();
3439 static ex H_series(const ex& m, const ex& x, const relational& rel, int order, unsigned options)
3441 epvector seq { expair(H(m, x), 0) };
3442 return pseries(rel, std::move(seq));
3446 static ex H_deriv(const ex& m_, const ex& x, unsigned deriv_param)
3448 GINAC_ASSERT(deriv_param < 2);
3449 if (deriv_param == 0) {
3453 if (is_a<lst>(m_)) {
3469 return 1/(1-x) * H(m, x);
3470 } else if (mb == _ex_1) {
3471 return 1/(1+x) * H(m, x);
3478 static void H_print_latex(const ex& m_, const ex& x, const print_context& c)
3481 if (is_a<lst>(m_)) {
3486 c.s << "\\mathrm{H}_{";
3487 auto itm = m.begin();
3490 for (; itm != m.end(); itm++) {
3500 REGISTER_FUNCTION(H,
3501 evalf_func(H_evalf).
3503 series_func(H_series).
3504 derivative_func(H_deriv).
3505 print_func<print_latex>(H_print_latex).
3506 do_not_evalf_params());
3509 // takes a parameter list for H and returns an expression with corresponding multiple polylogarithms
3510 ex convert_H_to_Li(const ex& m, const ex& x)
3512 map_trafo_H_reduce_trailing_zeros filter;
3513 map_trafo_H_convert_to_Li filter2;
3515 return filter2(filter(H(m, x).hold()));
3517 return filter2(filter(H(lst{m}, x).hold()));
3522 //////////////////////////////////////////////////////////////////////
3524 // Multiple zeta values zeta(x) and zeta(x,s)
3528 //////////////////////////////////////////////////////////////////////
3531 // anonymous namespace for helper functions
3535 // parameters and data for [Cra] algorithm
3536 const cln::cl_N lambda = cln::cl_N("319/320");
3538 void halfcyclic_convolute(const std::vector<cln::cl_N>& a, const std::vector<cln::cl_N>& b, std::vector<cln::cl_N>& c)
3540 const int size = a.size();
3541 for (int n=0; n<size; n++) {
3543 for (int m=0; m<=n; m++) {
3544 c[n] = c[n] + a[m]*b[n-m];
3551 static void initcX(std::vector<cln::cl_N>& crX,
3552 const std::vector<int>& s,
3555 std::vector<cln::cl_N> crB(L2 + 1);
3556 for (int i=0; i<=L2; i++)
3557 crB[i] = bernoulli(i).to_cl_N() / cln::factorial(i);
3561 std::vector<std::vector<cln::cl_N>> crG(s.size() - 1, std::vector<cln::cl_N>(L2 + 1));
3562 for (int m=0; m < (int)s.size() - 1; m++) {
3565 for (int i = 0; i <= L2; i++)
3566 crG[m][i] = cln::factorial(i + Sm - m - 2) / cln::factorial(i + Smp1 - m - 2);
3571 for (std::size_t m = 0; m < s.size() - 1; m++) {
3572 std::vector<cln::cl_N> Xbuf(L2 + 1);
3573 for (int i = 0; i <= L2; i++)
3574 Xbuf[i] = crX[i] * crG[m][i];
3576 halfcyclic_convolute(Xbuf, crB, crX);
3582 static cln::cl_N crandall_Y_loop(const cln::cl_N& Sqk,
3583 const std::vector<cln::cl_N>& crX)
3585 cln::cl_F one = cln::cl_float(1, cln::float_format(Digits));
3586 cln::cl_N factor = cln::expt(lambda, Sqk);
3587 cln::cl_N res = factor / Sqk * crX[0] * one;
3592 factor = factor * lambda;
3594 res = res + crX[N] * factor / (N+Sqk);
3595 } while ((res != resbuf) || cln::zerop(crX[N]));
3601 static void calc_f(std::vector<std::vector<cln::cl_N>>& f_kj,
3602 const int maxr, const int L1)
3604 cln::cl_N t0, t1, t2, t3, t4;
3606 auto it = f_kj.begin();
3607 cln::cl_F one = cln::cl_float(1, cln::float_format(Digits));
3609 t0 = cln::exp(-lambda);
3611 for (k=1; k<=L1; k++) {
3614 for (j=1; j<=maxr; j++) {
3617 for (i=2; i<=j; i++) {
3621 (*it).push_back(t2 * t3 * cln::expt(cln::cl_I(k),-j) * one);
3629 static cln::cl_N crandall_Z(const std::vector<int>& s,
3630 const std::vector<std::vector<cln::cl_N>>& f_kj)
3632 const int j = s.size();
3641 t0 = t0 + f_kj[q+j-2][s[0]-1];
3642 } while (t0 != t0buf);
3644 return t0 / cln::factorial(s[0]-1);
3647 std::vector<cln::cl_N> t(j);
3654 t[j-1] = t[j-1] + 1 / cln::expt(cln::cl_I(q),s[j-1]);
3655 for (int k=j-2; k>=1; k--) {
3656 t[k] = t[k] + t[k+1] / cln::expt(cln::cl_I(q+j-1-k), s[k]);
3658 t[0] = t[0] + t[1] * f_kj[q+j-2][s[0]-1];
3659 } while (t[0] != t0buf);
3661 return t[0] / cln::factorial(s[0]-1);
3666 cln::cl_N zeta_do_sum_Crandall(const std::vector<int>& s)
3668 std::vector<int> r = s;
3669 const int j = r.size();
3673 // decide on maximal size of f_kj for crandall_Z
3677 L1 = Digits * 3 + j*2;
3681 // decide on maximal size of crX for crandall_Y
3684 } else if (Digits < 86) {
3686 } else if (Digits < 192) {
3688 } else if (Digits < 394) {
3690 } else if (Digits < 808) {
3700 for (int i=0; i<j; i++) {
3707 std::vector<std::vector<cln::cl_N>> f_kj(L1);
3708 calc_f(f_kj, maxr, L1);
3710 const cln::cl_N r0factorial = cln::factorial(r[0]-1);
3712 std::vector<int> rz;
3715 for (int k=r.size()-1; k>0; k--) {
3717 rz.insert(rz.begin(), r.back());
3718 skp1buf = rz.front();
3722 std::vector<cln::cl_N> crX;
3725 for (int q=0; q<skp1buf; q++) {
3727 cln::cl_N pp1 = crandall_Y_loop(Srun+q-k, crX);
3728 cln::cl_N pp2 = crandall_Z(rz, f_kj);
3733 res = res - pp1 * pp2 / cln::factorial(q);
3735 res = res + pp1 * pp2 / cln::factorial(q);
3738 rz.front() = skp1buf;
3740 rz.insert(rz.begin(), r.back());
3742 std::vector<cln::cl_N> crX;
3743 initcX(crX, rz, L2);
3745 res = (res + crandall_Y_loop(S-j, crX)) / r0factorial
3746 + crandall_Z(rz, f_kj);
3752 cln::cl_N zeta_do_sum_simple(const std::vector<int>& r)
3754 const int j = r.size();
3756 // buffer for subsums
3757 std::vector<cln::cl_N> t(j);
3758 cln::cl_F one = cln::cl_float(1, cln::float_format(Digits));
3765 t[j-1] = t[j-1] + one / cln::expt(cln::cl_I(q),r[j-1]);
3766 for (int k=j-2; k>=0; k--) {
3767 t[k] = t[k] + one * t[k+1] / cln::expt(cln::cl_I(q+j-1-k), r[k]);
3769 } while (t[0] != t0buf);
3775 // does Hoelder convolution. see [BBB] (7.0)
3776 cln::cl_N zeta_do_Hoelder_convolution(const std::vector<int>& m_, const std::vector<int>& s_)
3778 // prepare parameters
3779 // holds Li arguments in [BBB] notation
3780 std::vector<int> s = s_;
3781 std::vector<int> m_p = m_;
3782 std::vector<int> m_q;
3783 // holds Li arguments in nested sums notation
3784 std::vector<cln::cl_N> s_p(s.size(), cln::cl_N(1));
3785 s_p[0] = s_p[0] * cln::cl_N("1/2");
3786 // convert notations
3788 for (std::size_t i = 0; i < s_.size(); i++) {
3793 s[i] = sig * std::abs(s[i]);
3795 std::vector<cln::cl_N> s_q;
3796 cln::cl_N signum = 1;
3799 cln::cl_N res = multipleLi_do_sum(m_p, s_p);
3804 // change parameters
3805 if (s.front() > 0) {
3806 if (m_p.front() == 1) {
3807 m_p.erase(m_p.begin());
3808 s_p.erase(s_p.begin());
3809 if (s_p.size() > 0) {
3810 s_p.front() = s_p.front() * cln::cl_N("1/2");
3816 m_q.insert(m_q.begin(), 1);
3817 if (s_q.size() > 0) {
3818 s_q.front() = s_q.front() * 2;
3820 s_q.insert(s_q.begin(), cln::cl_N("1/2"));
3823 if (m_p.front() == 1) {
3824 m_p.erase(m_p.begin());
3825 cln::cl_N spbuf = s_p.front();
3826 s_p.erase(s_p.begin());
3827 if (s_p.size() > 0) {
3828 s_p.front() = s_p.front() * spbuf;
3831 m_q.insert(m_q.begin(), 1);
3832 if (s_q.size() > 0) {
3833 s_q.front() = s_q.front() * 4;
3835 s_q.insert(s_q.begin(), cln::cl_N("1/4"));
3839 m_q.insert(m_q.begin(), 1);
3840 if (s_q.size() > 0) {
3841 s_q.front() = s_q.front() * 2;
3843 s_q.insert(s_q.begin(), cln::cl_N("1/2"));
3848 if (m_p.size() == 0) break;
3850 res = res + signum * multipleLi_do_sum(m_p, s_p) * multipleLi_do_sum(m_q, s_q);
3855 res = res + signum * multipleLi_do_sum(m_q, s_q);
3861 } // end of anonymous namespace
3864 //////////////////////////////////////////////////////////////////////
3866 // Multiple zeta values zeta(x)
3870 //////////////////////////////////////////////////////////////////////
3873 static ex zeta1_evalf(const ex& x)
3875 if (is_exactly_a<lst>(x) && (x.nops()>1)) {
3877 // multiple zeta value
3878 const int count = x.nops();
3879 const lst& xlst = ex_to<lst>(x);
3880 std::vector<int> r(count);
3882 // check parameters and convert them
3883 auto it1 = xlst.begin();
3884 auto it2 = r.begin();
3886 if (!(*it1).info(info_flags::posint)) {
3887 return zeta(x).hold();
3889 *it2 = ex_to<numeric>(*it1).to_int();
3892 } while (it2 != r.end());
3894 // check for divergence
3896 return zeta(x).hold();
3899 // decide on summation algorithm
3900 // this is still a bit clumsy
3901 int limit = (Digits>17) ? 10 : 6;
3902 if ((r[0] < limit) || ((count > 3) && (r[1] < limit/2))) {
3903 return numeric(zeta_do_sum_Crandall(r));
3905 return numeric(zeta_do_sum_simple(r));
3909 // single zeta value
3910 if (is_exactly_a<numeric>(x) && (x != 1)) {
3912 return zeta(ex_to<numeric>(x));
3913 } catch (const dunno &e) { }
3916 return zeta(x).hold();
3920 static ex zeta1_eval(const ex& m)
3922 if (is_exactly_a<lst>(m)) {
3923 if (m.nops() == 1) {
3924 return zeta(m.op(0));
3926 return zeta(m).hold();
3929 if (m.info(info_flags::numeric)) {
3930 const numeric& y = ex_to<numeric>(m);
3931 // trap integer arguments:
3932 if (y.is_integer()) {
3936 if (y.is_equal(*_num1_p)) {
3937 return zeta(m).hold();
3939 if (y.info(info_flags::posint)) {
3940 if (y.info(info_flags::odd)) {
3941 return zeta(m).hold();
3943 return abs(bernoulli(y)) * pow(Pi, y) * pow(*_num2_p, y-(*_num1_p)) / factorial(y);
3946 if (y.info(info_flags::odd)) {
3947 return -bernoulli((*_num1_p)-y) / ((*_num1_p)-y);
3954 if (y.info(info_flags::numeric) && !y.info(info_flags::crational)) {
3955 return zeta1_evalf(m);
3958 return zeta(m).hold();
3962 static ex zeta1_deriv(const ex& m, unsigned deriv_param)
3964 GINAC_ASSERT(deriv_param==0);
3966 if (is_exactly_a<lst>(m)) {
3969 return zetaderiv(_ex1, m);
3974 static void zeta1_print_latex(const ex& m_, const print_context& c)
3977 if (is_a<lst>(m_)) {
3978 const lst& m = ex_to<lst>(m_);
3979 auto it = m.begin();
3982 for (; it != m.end(); it++) {
3993 unsigned zeta1_SERIAL::serial = function::register_new(function_options("zeta", 1).
3994 evalf_func(zeta1_evalf).
3995 eval_func(zeta1_eval).
3996 derivative_func(zeta1_deriv).
3997 print_func<print_latex>(zeta1_print_latex).
3998 do_not_evalf_params().
4002 //////////////////////////////////////////////////////////////////////
4004 // Alternating Euler sum zeta(x,s)
4008 //////////////////////////////////////////////////////////////////////
4011 static ex zeta2_evalf(const ex& x, const ex& s)
4013 if (is_exactly_a<lst>(x)) {
4015 // alternating Euler sum
4016 const int count = x.nops();
4017 const lst& xlst = ex_to<lst>(x);
4018 const lst& slst = ex_to<lst>(s);
4019 std::vector<int> xi(count);
4020 std::vector<int> si(count);
4022 // check parameters and convert them
4023 auto it_xread = xlst.begin();
4024 auto it_sread = slst.begin();
4025 auto it_xwrite = xi.begin();
4026 auto it_swrite = si.begin();
4028 if (!(*it_xread).info(info_flags::posint)) {
4029 return zeta(x, s).hold();
4031 *it_xwrite = ex_to<numeric>(*it_xread).to_int();
4032 if (*it_sread > 0) {
4041 } while (it_xwrite != xi.end());
4043 // check for divergence
4044 if ((xi[0] == 1) && (si[0] == 1)) {
4045 return zeta(x, s).hold();
4048 // use Hoelder convolution
4049 return numeric(zeta_do_Hoelder_convolution(xi, si));
4052 return zeta(x, s).hold();
4056 static ex zeta2_eval(const ex& m, const ex& s_)
4058 if (is_exactly_a<lst>(s_)) {
4059 const lst& s = ex_to<lst>(s_);
4060 for (const auto & it : s) {
4061 if (it.info(info_flags::positive)) {
4064 return zeta(m, s_).hold();
4067 } else if (s_.info(info_flags::positive)) {
4071 return zeta(m, s_).hold();
4075 static ex zeta2_deriv(const ex& m, const ex& s, unsigned deriv_param)
4077 GINAC_ASSERT(deriv_param==0);
4079 if (is_exactly_a<lst>(m)) {
4082 if ((is_exactly_a<lst>(s) && s.op(0).info(info_flags::positive)) || s.info(info_flags::positive)) {
4083 return zetaderiv(_ex1, m);
4090 static void zeta2_print_latex(const ex& m_, const ex& s_, const print_context& c)
4093 if (is_a<lst>(m_)) {
4099 if (is_a<lst>(s_)) {
4105 auto itm = m.begin();
4106 auto its = s.begin();
4108 c.s << "\\overline{";
4116 for (; itm != m.end(); itm++, its++) {
4119 c.s << "\\overline{";
4130 unsigned zeta2_SERIAL::serial = function::register_new(function_options("zeta", 2).
4131 evalf_func(zeta2_evalf).
4132 eval_func(zeta2_eval).
4133 derivative_func(zeta2_deriv).
4134 print_func<print_latex>(zeta2_print_latex).
4135 do_not_evalf_params().
4139 } // namespace GiNaC