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 * nielsen's generalized polylogarithm S(n,p,x)
9 * harmonic polylogarithm H(m,x) or H(lst(m_1,...,m_k),x)
10 * multiple zeta value zeta(m) or zeta(lst(m_1,...,m_k))
11 * alternating Euler sum zeta(m,s) or zeta(lst(m_1,...,m_k),lst(s_1,...,s_k))
15 * - All formulae used can be looked up in the following publications:
16 * [Kol] Nielsen's Generalized Polylogarithms, K.S.Kolbig, SIAM J.Math.Anal. 17 (1986), pp. 1232-1258.
17 * [Cra] Fast Evaluation of Multiple Zeta Sums, R.E.Crandall, Math.Comp. 67 (1998), pp. 1163-1172.
18 * [ReV] Harmonic Polylogarithms, E.Remiddi, J.A.M.Vermaseren, Int.J.Mod.Phys. A15 (2000), pp. 725-754
19 * [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 * - The order of parameters and arguments of H, Li and zeta is defined according to their order in the
22 * nested sums representation.
24 * - Except for the multiple polylogarithm all functions can be nummerically evaluated with arguments in
25 * the whole complex plane. Multiple polylogarithms evaluate only if each argument x_i is smaller than
26 * one. The parameters for every function (n, p or n_i) must be positive integers.
28 * - The calculation of classical polylogarithms is speed up by using Bernoulli numbers and
29 * look-up tables. S uses look-up tables as well. The zeta function applies the algorithms in
30 * [Cra] and [BBB] for speed up.
32 * - The functions have no series expansion as nested sums. To do it, you have to convert these functions
33 * into the appropriate objects from the nestedsums library, do the expansion and convert the
36 * - Numerical testing of this implementation has been performed by doing a comparison of results
37 * between this software and the commercial M.......... 4.1. Multiple zeta values have been checked
38 * by means of evaluations into simple zeta values. Harmonic polylogarithms have been checked by
39 * comparison to S(n,p,x) for corresponding parameter combinations and by continuity checks
40 * around |x|=1 along with comparisons to corresponding zeta functions.
45 * GiNaC Copyright (C) 1999-2003 Johannes Gutenberg University Mainz, Germany
47 * This program is free software; you can redistribute it and/or modify
48 * it under the terms of the GNU General Public License as published by
49 * the Free Software Foundation; either version 2 of the License, or
50 * (at your option) any later version.
52 * This program is distributed in the hope that it will be useful,
53 * but WITHOUT ANY WARRANTY; without even the implied warranty of
54 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
55 * GNU General Public License for more details.
57 * You should have received a copy of the GNU General Public License
58 * along with this program; if not, write to the Free Software
59 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
73 #include "operators.h"
76 #include "relational.h"
85 //////////////////////////////////////////////////////////////////////
87 // Classical polylogarithm Li(n,x)
91 //////////////////////////////////////////////////////////////////////
94 // anonymous namespace for helper functions
98 // lookup table for factors built from Bernoulli numbers
100 std::vector<std::vector<cln::cl_N> > Xn;
104 // This function calculates the X_n. The X_n are needed for speed up of classical polylogarithms.
105 // With these numbers the polylogs can be calculated as follows:
106 // Li_p (x) = \sum_{n=0}^\infty X_{p-2}(n) u^{n+1}/(n+1)! with u = -log(1-x)
107 // X_0(n) = B_n (Bernoulli numbers)
108 // X_p(n) = \sum_{k=0}^n binomial(n,k) B_{n-k} / (k+1) * X_{p-1}(k)
109 // The calculation of Xn depends on X0 and X{n-1}.
110 // X_0 is special, it holds only the non-zero Bernoulli numbers with index 2 or greater.
111 // This results in a slightly more complicated algorithm for the X_n.
112 // The first index in Xn corresponds to the index of the polylog minus 2.
113 // The second index in Xn corresponds to the index from the actual sum.
116 // rule of thumb. needs to be improved. TODO
117 const int initsize = Digits * 3 / 2;
120 // calculate X_2 and higher (corresponding to Li_4 and higher)
121 std::vector<cln::cl_N> buf(initsize);
122 std::vector<cln::cl_N>::iterator it = buf.begin();
124 *it = -(cln::expt(cln::cl_I(2),n+1) - 1) / cln::expt(cln::cl_I(2),n+1); // i == 1
126 for (int i=2; i<=initsize; i++) {
128 result = 0; // k == 0
130 result = Xn[0][i/2-1]; // k == 0
132 for (int k=1; k<i-1; k++) {
133 if ( !(((i-k) & 1) && ((i-k) > 1)) ) {
134 result = result + cln::binomial(i,k) * Xn[0][(i-k)/2-1] * Xn[n-1][k-1] / (k+1);
137 result = result - cln::binomial(i,i-1) * Xn[n-1][i-2] / 2 / i; // k == i-1
138 result = result + Xn[n-1][i-1] / (i+1); // k == i
145 // special case to handle the X_0 correct
146 std::vector<cln::cl_N> buf(initsize);
147 std::vector<cln::cl_N>::iterator it = buf.begin();
149 *it = cln::cl_I(-3)/cln::cl_I(4); // i == 1
151 *it = cln::cl_I(17)/cln::cl_I(36); // i == 2
153 for (int i=3; i<=initsize; i++) {
155 result = -Xn[0][(i-3)/2]/2;
156 *it = (cln::binomial(i,1)/cln::cl_I(2) + cln::binomial(i,i-1)/cln::cl_I(i))*result;
159 result = Xn[0][i/2-1] + Xn[0][i/2-1]/(i+1);
160 for (int k=1; k<i/2; k++) {
161 result = result + cln::binomial(i,k*2) * Xn[0][k-1] * Xn[0][i/2-k-1] / (k*2+1);
170 std::vector<cln::cl_N> buf(initsize/2);
171 std::vector<cln::cl_N>::iterator it = buf.begin();
172 for (int i=1; i<=initsize/2; i++) {
173 *it = bernoulli(i*2).to_cl_N();
183 // calculates Li(2,x) without Xn
184 cln::cl_N Li2_do_sum(const cln::cl_N& x)
189 cln::cl_I den = 1; // n^2 = 1
194 den = den + i; // n^2 = 4, 9, 16, ...
196 res = res + num / den;
197 } while (res != resbuf);
202 // calculates Li(2,x) with Xn
203 cln::cl_N Li2_do_sum_Xn(const cln::cl_N& x)
205 std::vector<cln::cl_N>::const_iterator it = Xn[0].begin();
206 cln::cl_N u = -cln::log(1-x);
207 cln::cl_N factor = u;
208 cln::cl_N res = u - u*u/4;
213 factor = factor * u*u / (2*i * (2*i+1));
214 res = res + (*it) * factor;
215 it++; // should we check it? or rely on initsize? ...
217 } while (res != resbuf);
222 // calculates Li(n,x), n>2 without Xn
223 cln::cl_N Lin_do_sum(int n, const cln::cl_N& x)
225 cln::cl_N factor = x;
232 res = res + factor / cln::expt(cln::cl_I(i),n);
234 } while (res != resbuf);
239 // calculates Li(n,x), n>2 with Xn
240 cln::cl_N Lin_do_sum_Xn(int n, const cln::cl_N& x)
242 std::vector<cln::cl_N>::const_iterator it = Xn[n-2].begin();
243 cln::cl_N u = -cln::log(1-x);
244 cln::cl_N factor = u;
250 factor = factor * u / i;
251 res = res + (*it) * factor;
252 it++; // should we check it? or rely on initsize? ...
254 } while (res != resbuf);
259 // forward declaration needed by function Li_projection and C below
260 numeric S_num(int n, int p, const numeric& x);
263 // helper function for classical polylog Li
264 cln::cl_N Li_projection(int n, const cln::cl_N& x, const cln::float_format_t& prec)
266 // treat n=2 as special case
268 // check if precalculated X0 exists
273 if (cln::realpart(x) < 0.5) {
274 // choose the faster algorithm
275 // the switching point was empirically determined. the optimal point
276 // depends on hardware, Digits, ... so an approx value is okay.
277 // it solves also the problem with precision due to the u=-log(1-x) transformation
278 if (cln::abs(cln::realpart(x)) < 0.25) {
280 return Li2_do_sum(x);
282 return Li2_do_sum_Xn(x);
285 // choose the faster algorithm
286 if (cln::abs(cln::realpart(x)) > 0.75) {
287 return -Li2_do_sum(1-x) - cln::log(x) * cln::log(1-x) + cln::zeta(2);
289 return -Li2_do_sum_Xn(1-x) - cln::log(x) * cln::log(1-x) + cln::zeta(2);
293 // check if precalculated Xn exist
295 for (int i=xnsize; i<n-1; i++) {
300 if (cln::realpart(x) < 0.5) {
301 // choose the faster algorithm
302 // with n>=12 the "normal" summation always wins against the method with Xn
303 if ((cln::abs(cln::realpart(x)) < 0.3) || (n >= 12)) {
304 return Lin_do_sum(n, x);
306 return Lin_do_sum_Xn(n, x);
309 cln::cl_N result = -cln::expt(cln::log(x), n-1) * cln::log(1-x) / cln::factorial(n-1);
310 for (int j=0; j<n-1; j++) {
311 result = result + (S_num(n-j-1, 1, 1).to_cl_N() - S_num(1, n-j-1, 1-x).to_cl_N())
312 * cln::expt(cln::log(x), j) / cln::factorial(j);
320 // helper function for classical polylog Li
321 numeric Li_num(int n, const numeric& x)
325 return -cln::log(1-x.to_cl_N());
336 return -(1-cln::expt(cln::cl_I(2),1-n)) * cln::zeta(n);
339 // what is the desired float format?
340 // first guess: default format
341 cln::float_format_t prec = cln::default_float_format;
342 const cln::cl_N value = x.to_cl_N();
343 // second guess: the argument's format
344 if (!x.real().is_rational())
345 prec = cln::float_format(cln::the<cln::cl_F>(cln::realpart(value)));
346 else if (!x.imag().is_rational())
347 prec = cln::float_format(cln::the<cln::cl_F>(cln::imagpart(value)));
350 if (cln::abs(value) > 1) {
351 cln::cl_N result = -cln::expt(cln::log(-value),n) / cln::factorial(n);
352 // check if argument is complex. if it is real, the new polylog has to be conjugated.
353 if (cln::zerop(cln::imagpart(value))) {
355 result = result + conjugate(Li_projection(n, cln::recip(value), prec));
358 result = result - conjugate(Li_projection(n, cln::recip(value), prec));
363 result = result + Li_projection(n, cln::recip(value), prec);
366 result = result - Li_projection(n, cln::recip(value), prec);
370 for (int j=0; j<n-1; j++) {
371 add = add + (1+cln::expt(cln::cl_I(-1),n-j)) * (1-cln::expt(cln::cl_I(2),1-n+j))
372 * Li_num(n-j,1).to_cl_N() * cln::expt(cln::log(-value),j) / cln::factorial(j);
374 result = result - add;
378 return Li_projection(n, value, prec);
383 } // end of anonymous namespace
386 //////////////////////////////////////////////////////////////////////
388 // Multiple polylogarithm Li(n,x)
392 //////////////////////////////////////////////////////////////////////
395 // anonymous namespace for helper function
399 cln::cl_N multipleLi_do_sum(const std::vector<int>& s, const std::vector<cln::cl_N>& x)
401 const int j = s.size();
403 std::vector<cln::cl_N> t(j);
404 cln::cl_F one = cln::cl_float(1, cln::float_format(Digits));
411 t[j-1] = t[j-1] + cln::expt(x[j-1], q) / cln::expt(cln::cl_I(q),s[j-1]) * one;
412 for (int k=j-2; k>=0; k--) {
413 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]);
415 } while ((t[0] != t0buf) || (q<10));
421 } // end of anonymous namespace
424 //////////////////////////////////////////////////////////////////////
426 // Classical polylogarithm and multiple polylogarithm Li(n,x)
430 //////////////////////////////////////////////////////////////////////
433 static ex Li_eval(const ex& x1, const ex& x2)
439 if (x2.info(info_flags::numeric) && (!x2.info(info_flags::crational)))
440 return Li_num(ex_to<numeric>(x1).to_int(), ex_to<numeric>(x2));
442 for (int i=0; i<x2.nops(); i++) {
443 if (!is_a<numeric>(x2.op(i))) {
444 return Li(x1,x2).hold();
447 return Li(x1,x2).evalf();
449 return Li(x1,x2).hold();
454 static ex Li_evalf(const ex& x1, const ex& x2)
456 // classical polylogs
457 if (is_a<numeric>(x1) && is_a<numeric>(x2)) {
458 return Li_num(ex_to<numeric>(x1).to_int(), ex_to<numeric>(x2));
461 else if (is_a<lst>(x1) && is_a<lst>(x2)) {
463 for (int i=0; i<x1.nops(); i++) {
464 if (!x1.op(i).info(info_flags::posint)) {
465 return Li(x1,x2).hold();
467 if (!is_a<numeric>(x2.op(i))) {
468 return Li(x1,x2).hold();
471 if ((conv > 1) || ((conv == 1) && (x1.op(0) == 1))) {
472 return Li(x1,x2).hold();
477 std::vector<cln::cl_N> x;
478 for (int i=0; i<ex_to<numeric>(x1.nops()).to_int(); i++) {
479 m.push_back(ex_to<numeric>(x1.op(i)).to_int());
480 x.push_back(ex_to<numeric>(x2.op(i)).to_cl_N());
483 return numeric(multipleLi_do_sum(m, x));
486 return Li(x1,x2).hold();
490 static ex Li_series(const ex& x1, const ex& x2, const relational& rel, int order, unsigned options)
493 seq.push_back(expair(Li(x1,x2), 0));
494 return pseries(rel,seq);
498 static ex Li_deriv(const ex& x1, const ex& x2, unsigned deriv_param)
500 GINAC_ASSERT(deriv_param < 2);
501 if (deriv_param == 0) {
505 return Li(x1-1, x2) / x2;
512 REGISTER_FUNCTION(Li,
514 evalf_func(Li_evalf).
515 do_not_evalf_params().
516 series_func(Li_series).
517 derivative_func(Li_deriv));
520 //////////////////////////////////////////////////////////////////////
522 // Nielsen's generalized polylogarithm S(n,p,x)
526 //////////////////////////////////////////////////////////////////////
529 // anonymous namespace for helper functions
533 // lookup table for special Euler-Zagier-Sums (used for S_n,p(x))
535 std::vector<std::vector<cln::cl_N> > Yn;
536 int ynsize = 0; // number of Yn[]
537 int ynlength = 100; // initial length of all Yn[i]
540 // This function calculates the Y_n. The Y_n are needed for the evaluation of S_{n,p}(x).
541 // The Y_n are basically Euler-Zagier sums with all m_i=1. They are subsums in the Z-sum
542 // representing S_{n,p}(x).
543 // The first index in Y_n corresponds to the parameter p minus one, i.e. the depth of the
545 // The second index in Y_n corresponds to the running index of the outermost sum in the full Z-sum
546 // representing S_{n,p}(x).
547 // The calculation of Y_n uses the values from Y_{n-1}.
548 void fill_Yn(int n, const cln::float_format_t& prec)
550 const int initsize = ynlength;
551 //const int initsize = initsize_Yn;
552 cln::cl_N one = cln::cl_float(1, prec);
555 std::vector<cln::cl_N> buf(initsize);
556 std::vector<cln::cl_N>::iterator it = buf.begin();
557 std::vector<cln::cl_N>::iterator itprev = Yn[n-1].begin();
558 *it = (*itprev) / cln::cl_N(n+1) * one;
561 // sums with an index smaller than the depth are zero and need not to be calculated.
562 // calculation starts with depth, which is n+2)
563 for (int i=n+2; i<=initsize+n; i++) {
564 *it = *(it-1) + (*itprev) / cln::cl_N(i) * one;
570 std::vector<cln::cl_N> buf(initsize);
571 std::vector<cln::cl_N>::iterator it = buf.begin();
574 for (int i=2; i<=initsize; i++) {
575 *it = *(it-1) + 1 / cln::cl_N(i) * one;
584 // make Yn longer ...
585 void make_Yn_longer(int newsize, const cln::float_format_t& prec)
588 cln::cl_N one = cln::cl_float(1, prec);
590 Yn[0].resize(newsize);
591 std::vector<cln::cl_N>::iterator it = Yn[0].begin();
593 for (int i=ynlength+1; i<=newsize; i++) {
594 *it = *(it-1) + 1 / cln::cl_N(i) * one;
598 for (int n=1; n<ynsize; n++) {
599 Yn[n].resize(newsize);
600 std::vector<cln::cl_N>::iterator it = Yn[n].begin();
601 std::vector<cln::cl_N>::iterator itprev = Yn[n-1].begin();
604 for (int i=ynlength+n+1; i<=newsize+n; i++) {
605 *it = *(it-1) + (*itprev) / cln::cl_N(i) * one;
615 // helper function for S(n,p,x)
617 cln::cl_N C(int n, int p)
621 for (int k=0; k<p; k++) {
622 for (int j=0; j<=(n+k-1)/2; j++) {
626 result = result - 2 * cln::expt(cln::pi(),2*j) * S_num(n-2*j,p,1).to_cl_N() / cln::factorial(2*j);
629 result = result + 2 * cln::expt(cln::pi(),2*j) * S_num(n-2*j,p,1).to_cl_N() / cln::factorial(2*j);
636 result = result + cln::factorial(n+k-1)
637 * cln::expt(cln::pi(),2*j) * S_num(n+k-2*j,p-k,1).to_cl_N()
638 / (cln::factorial(k) * cln::factorial(n-1) * cln::factorial(2*j));
641 result = result - cln::factorial(n+k-1)
642 * cln::expt(cln::pi(),2*j) * S_num(n+k-2*j,p-k,1).to_cl_N()
643 / (cln::factorial(k) * cln::factorial(n-1) * cln::factorial(2*j));
648 result = result - cln::factorial(n+k-1) * cln::expt(cln::pi(),2*j) * S_num(n+k-2*j,p-k,1).to_cl_N()
649 / (cln::factorial(k) * cln::factorial(n-1) * cln::factorial(2*j));
652 result = result + cln::factorial(n+k-1)
653 * cln::expt(cln::pi(),2*j) * S_num(n+k-2*j,p-k,1).to_cl_N()
654 / (cln::factorial(k) * cln::factorial(n-1) * cln::factorial(2*j));
662 if (((np)/2+n) & 1) {
663 result = -result - cln::expt(cln::pi(),np) / (np * cln::factorial(n-1) * cln::factorial(p));
666 result = -result + cln::expt(cln::pi(),np) / (np * cln::factorial(n-1) * cln::factorial(p));
674 // helper function for S(n,p,x)
675 // [Kol] remark to (9.1)
685 for (int m=2; m<=k; m++) {
686 result = result + cln::expt(cln::cl_N(-1),m) * cln::zeta(m) * a_k(k-m);
693 // helper function for S(n,p,x)
694 // [Kol] remark to (9.1)
704 for (int m=2; m<=k; m++) {
705 result = result + cln::expt(cln::cl_N(-1),m) * cln::zeta(m) * b_k(k-m);
712 // helper function for S(n,p,x)
713 cln::cl_N S_do_sum(int n, int p, const cln::cl_N& x, const cln::float_format_t& prec)
716 return Li_projection(n+1, x, prec);
719 // check if precalculated values are sufficient
721 for (int i=ynsize; i<p-1; i++) {
726 // should be done otherwise
727 cln::cl_N xf = x * cln::cl_float(1, prec);
731 cln::cl_N factor = cln::expt(xf, p);
735 if (i-p >= ynlength) {
737 make_Yn_longer(ynlength*2, prec);
739 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? ...
740 //res = res + factor / cln::expt(cln::cl_I(i),n+1) * (*it); // should we check it? or rely on magic number? ...
741 factor = factor * xf;
743 } while (res != resbuf);
749 // helper function for S(n,p,x)
750 cln::cl_N S_projection(int n, int p, const cln::cl_N& x, const cln::float_format_t& prec)
753 if (cln::abs(cln::realpart(x)) > cln::cl_F("0.5")) {
755 cln::cl_N result = cln::expt(cln::cl_I(-1),p) * cln::expt(cln::log(x),n)
756 * cln::expt(cln::log(1-x),p) / cln::factorial(n) / cln::factorial(p);
758 for (int s=0; s<n; s++) {
760 for (int r=0; r<p; r++) {
761 res2 = res2 + cln::expt(cln::cl_I(-1),r) * cln::expt(cln::log(1-x),r)
762 * S_do_sum(p-r,n-s,1-x,prec) / cln::factorial(r);
764 result = result + cln::expt(cln::log(x),s) * (S_num(n-s,p,1).to_cl_N() - res2) / cln::factorial(s);
770 return S_do_sum(n, p, x, prec);
774 // helper function for S(n,p,x)
775 numeric S_num(int n, int p, const numeric& x)
779 // [Kol] (2.22) with (2.21)
780 return cln::zeta(p+1);
785 return cln::zeta(n+1);
790 for (int nu=0; nu<n; nu++) {
791 for (int rho=0; rho<=p; rho++) {
792 result = result + b_k(n-nu-1) * b_k(p-rho) * a_k(nu+rho+1)
793 * cln::factorial(nu+rho+1) / cln::factorial(rho) / cln::factorial(nu+1);
796 result = result * cln::expt(cln::cl_I(-1),n+p-1);
803 return -(1-cln::expt(cln::cl_I(2),-n)) * cln::zeta(n+1);
805 // throw std::runtime_error("don't know how to evaluate this function!");
808 // what is the desired float format?
809 // first guess: default format
810 cln::float_format_t prec = cln::default_float_format;
811 const cln::cl_N value = x.to_cl_N();
812 // second guess: the argument's format
813 if (!x.real().is_rational())
814 prec = cln::float_format(cln::the<cln::cl_F>(cln::realpart(value)));
815 else if (!x.imag().is_rational())
816 prec = cln::float_format(cln::the<cln::cl_F>(cln::imagpart(value)));
820 if (cln::realpart(value) < -0.5) {
822 cln::cl_N result = cln::expt(cln::cl_I(-1),p) * cln::expt(cln::log(value),n)
823 * cln::expt(cln::log(1-value),p) / cln::factorial(n) / cln::factorial(p);
825 for (int s=0; s<n; s++) {
827 for (int r=0; r<p; r++) {
828 res2 = res2 + cln::expt(cln::cl_I(-1),r) * cln::expt(cln::log(1-value),r)
829 * S_num(p-r,n-s,1-value).to_cl_N() / cln::factorial(r);
831 result = result + cln::expt(cln::log(value),s) * (S_num(n-s,p,1).to_cl_N() - res2) / cln::factorial(s);
838 if (cln::abs(value) > 1) {
842 for (int s=0; s<p; s++) {
843 for (int r=0; r<=s; r++) {
844 result = result + cln::expt(cln::cl_I(-1),s) * cln::expt(cln::log(-value),r) * cln::factorial(n+s-r-1)
845 / cln::factorial(r) / cln::factorial(s-r) / cln::factorial(n-1)
846 * S_num(n+s-r,p-s,cln::recip(value)).to_cl_N();
849 result = result * cln::expt(cln::cl_I(-1),n);
852 for (int r=0; r<n; r++) {
853 res2 = res2 + cln::expt(cln::log(-value),r) * C(n-r,p) / cln::factorial(r);
855 res2 = res2 + cln::expt(cln::log(-value),n+p) / cln::factorial(n+p);
857 result = result + cln::expt(cln::cl_I(-1),p) * res2;
862 return S_projection(n, p, value, prec);
867 } // end of anonymous namespace
870 //////////////////////////////////////////////////////////////////////
872 // Nielsen's generalized polylogarithm S(n,p,x)
876 //////////////////////////////////////////////////////////////////////
879 static ex S_eval(const ex& x1, const ex& x2, const ex& x3)
884 if (x3.info(info_flags::numeric) && (!x3.info(info_flags::crational)) &&
885 x1.info(info_flags::posint) && x2.info(info_flags::posint)) {
886 return S_num(ex_to<numeric>(x1).to_int(), ex_to<numeric>(x2).to_int(), ex_to<numeric>(x3));
888 return S(x1,x2,x3).hold();
892 static ex S_evalf(const ex& x1, const ex& x2, const ex& x3)
894 if (is_a<numeric>(x1) && is_a<numeric>(x2) && is_a<numeric>(x3)) {
895 return S_num(ex_to<numeric>(x1).to_int(), ex_to<numeric>(x2).to_int(), ex_to<numeric>(x3));
897 return S(x1,x2,x3).hold();
901 static ex S_series(const ex& x1, const ex& x2, const ex& x3, const relational& rel, int order, unsigned options)
904 seq.push_back(expair(S(x1,x2,x3), 0));
905 return pseries(rel,seq);
909 static ex S_deriv(const ex& x1, const ex& x2, const ex& x3, unsigned deriv_param)
911 GINAC_ASSERT(deriv_param < 3);
912 if (deriv_param < 2) {
916 return S(x1-1, x2, x3) / x3;
918 return S(x1, x2-1, x3) / (1-x3);
926 do_not_evalf_params().
927 series_func(S_series).
928 derivative_func(S_deriv));
931 //////////////////////////////////////////////////////////////////////
933 // Harmonic polylogarithm H(m,x)
937 //////////////////////////////////////////////////////////////////////
940 // anonymous namespace for helper functions
944 // forward declaration
945 ex convert_from_RV(const lst& parameterlst, const ex& arg);
948 // multiplies an one-dimensional H with another H
950 ex trafo_H_mult(const ex& h1, const ex& h2)
955 ex h1nops = h1.op(0).nops();
956 ex h2nops = h2.op(0).nops();
958 hshort = h2.op(0).op(0);
959 hlong = ex_to<lst>(h1.op(0));
961 hshort = h1.op(0).op(0);
963 hlong = ex_to<lst>(h2.op(0));
965 hlong = h2.op(0).op(0);
968 for (int i=0; i<=hlong.nops(); i++) {
972 newparameter.append(hlong[j]);
974 newparameter.append(hshort);
975 for (; j<hlong.nops(); j++) {
976 newparameter.append(hlong[j]);
978 res += H(newparameter, h1.op(1)).hold();
984 // applies trafo_H_mult recursively on expressions
985 struct map_trafo_H_mult : public map_function
987 ex operator()(const ex& e)
998 for (int pos=0; pos<e.nops(); pos++) {
999 if (is_a<power>(e.op(pos)) && is_a<function>(e.op(pos).op(0))) {
1000 std::string name = ex_to<function>(e.op(pos).op(0)).get_name();
1002 for (ex i=0; i<e.op(pos).op(1); i++) {
1003 Hlst.append(e.op(pos).op(0));
1007 } else if (is_a<function>(e.op(pos))) {
1008 std::string name = ex_to<function>(e.op(pos)).get_name();
1010 if (e.op(pos).op(0).nops() > 1) {
1013 Hlst.append(e.op(pos));
1018 result *= e.op(pos);
1021 if (Hlst.nops() > 0) {
1022 firstH = Hlst[Hlst.nops()-1];
1029 if (Hlst.nops() > 0) {
1030 ex buffer = trafo_H_mult(firstH, Hlst.op(0));
1032 for (int i=1; i<Hlst.nops(); i++) {
1033 result *= Hlst.op(i);
1035 result = result.expand();
1036 map_trafo_H_mult recursion;
1037 return recursion(result);
1048 // do integration [ReV] (49)
1049 // put parameter 1 in front of existing parameters
1050 ex trafo_H_prepend_one(const ex& e, const ex& arg)
1054 if (is_a<function>(e)) {
1055 name = ex_to<function>(e).get_name();
1060 for (int i=0; i<e.nops(); i++) {
1061 if (is_a<function>(e.op(i))) {
1062 std::string name = ex_to<function>(e.op(i)).get_name();
1070 lst newparameter = ex_to<lst>(h.op(0));
1071 newparameter.prepend(1);
1072 return e.subs(h == H(newparameter, h.op(1)).hold());
1074 return e * H(lst(1),1-arg).hold();
1079 // do integration [ReV] (55)
1080 // put parameter 0 in front of existing parameters
1081 ex trafo_H_prepend_zero(const ex& e, const ex& arg)
1085 if (is_a<function>(e)) {
1086 name = ex_to<function>(e).get_name();
1091 for (int i=0; i<e.nops(); i++) {
1092 if (is_a<function>(e.op(i))) {
1093 std::string name = ex_to<function>(e.op(i)).get_name();
1101 lst newparameter = ex_to<lst>(h.op(0));
1102 newparameter.prepend(0);
1103 ex addzeta = convert_from_RV(newparameter, 1).subs(H(wild(1),wild(2))==zeta(wild(1)));
1104 return e.subs(h == (addzeta-H(newparameter, h.op(1)).hold())).expand();
1106 return e * (-H(lst(0),1/arg).hold());
1111 // do x -> 1-x transformation
1112 struct map_trafo_H_1mx : public map_function
1114 ex operator()(const ex& e)
1116 if (is_a<add>(e) || is_a<mul>(e)) {
1117 return e.map(*this);
1120 if (is_a<function>(e)) {
1121 std::string name = ex_to<function>(e).get_name();
1124 lst parameter = ex_to<lst>(e.op(0));
1127 // if all parameters are either zero or one return the transformed function
1128 if (find(parameter.begin(), parameter.end(), 0) == parameter.end()) {
1130 for (int i=parameter.nops(); i>0; i--) {
1131 newparameter.append(0);
1133 return pow(-1, parameter.nops()) * H(newparameter, 1-arg).hold();
1134 } else if (find(parameter.begin(), parameter.end(), 1) == parameter.end()) {
1136 for (int i=parameter.nops(); i>0; i--) {
1137 newparameter.append(1);
1139 return pow(-1, parameter.nops()) * H(newparameter, 1-arg).hold();
1142 lst newparameter = parameter;
1143 newparameter.remove_first();
1145 if (parameter.op(0) == 0) {
1148 ex res = convert_from_RV(parameter, 1).subs(H(wild(1),wild(2))==zeta(wild(1)));
1149 map_trafo_H_1mx recursion;
1150 ex buffer = recursion(H(newparameter, arg).hold());
1151 if (is_a<add>(buffer)) {
1152 for (int i=0; i<buffer.nops(); i++) {
1153 res -= trafo_H_prepend_one(buffer.op(i), arg);
1156 res -= trafo_H_prepend_one(buffer, arg);
1163 map_trafo_H_1mx recursion;
1164 map_trafo_H_mult unify;
1167 while (parameter.op(firstzero) == 1) {
1170 for (int i=firstzero-1; i<parameter.nops()-1; i++) {
1174 newparameter.append(parameter[j+1]);
1176 newparameter.append(1);
1177 for (; j<parameter.nops()-1; j++) {
1178 newparameter.append(parameter[j+1]);
1180 res -= H(newparameter, arg).hold();
1182 return (unify((-H(lst(0), 1-arg).hold() * recursion(H(newparameter, arg).hold())).expand()) +
1183 recursion(res)) / firstzero;
1194 // do x -> 1/x transformation
1195 struct map_trafo_H_1overx : public map_function
1197 ex operator()(const ex& e)
1199 if (is_a<add>(e) || is_a<mul>(e)) {
1200 return e.map(*this);
1203 if (is_a<function>(e)) {
1204 std::string name = ex_to<function>(e).get_name();
1207 lst parameter = ex_to<lst>(e.op(0));
1210 // if all parameters are either zero or one return the transformed function
1211 if (find(parameter.begin(), parameter.end(), 0) == parameter.end()) {
1212 map_trafo_H_mult unify;
1213 return unify((pow(H(lst(1),1/arg).hold() + H(lst(0),1/arg).hold() - I*Pi, parameter.nops()) /
1214 factorial(parameter.nops())).expand());
1215 } else if (find(parameter.begin(), parameter.end(), 1) == parameter.end()) {
1216 return pow(-1, parameter.nops()) * H(parameter, 1/arg).hold();
1219 lst newparameter = parameter;
1220 newparameter.remove_first();
1222 if (parameter.op(0) == 0) {
1225 ex res = convert_from_RV(parameter, 1).subs(H(wild(1),wild(2))==zeta(wild(1)));
1226 map_trafo_H_1overx recursion;
1227 ex buffer = recursion(H(newparameter, arg).hold());
1228 if (is_a<add>(buffer)) {
1229 for (int i=0; i<buffer.nops(); i++) {
1230 res += trafo_H_prepend_zero(buffer.op(i), arg);
1233 res += trafo_H_prepend_zero(buffer, arg);
1240 map_trafo_H_1overx recursion;
1241 map_trafo_H_mult unify;
1242 ex res = H(lst(1), arg).hold() * H(newparameter, arg).hold();
1244 while (parameter.op(firstzero) == 1) {
1247 for (int i=firstzero-1; i<parameter.nops()-1; i++) {
1251 newparameter.append(parameter[j+1]);
1253 newparameter.append(1);
1254 for (; j<parameter.nops()-1; j++) {
1255 newparameter.append(parameter[j+1]);
1257 res -= H(newparameter, arg).hold();
1259 res = recursion(res).expand() / firstzero;
1271 // remove trailing zeros from H-parameters
1272 struct map_trafo_H_reduce_trailing_zeros : public map_function
1274 ex operator()(const ex& e)
1276 if (is_a<add>(e) || is_a<mul>(e)) {
1277 return e.map(*this);
1279 if (is_a<function>(e)) {
1280 std::string name = ex_to<function>(e).get_name();
1283 if (is_a<lst>(e.op(0))) {
1284 parameter = ex_to<lst>(e.op(0));
1286 parameter = lst(e.op(0));
1289 if (parameter.op(parameter.nops()-1) == 0) {
1292 if (parameter.nops() == 1) {
1297 lst::const_iterator it = parameter.begin();
1298 while ((it != parameter.end()) && (*it == 0)) {
1301 if (it == parameter.end()) {
1302 return pow(log(arg),parameter.nops()) / factorial(parameter.nops());
1306 parameter.remove_last();
1307 int lastentry = parameter.nops();
1308 while ((lastentry > 0) && (parameter[lastentry-1] == 0)) {
1313 ex result = log(arg) * H(parameter,arg).hold();
1314 for (ex i=0; i<lastentry; i++) {
1316 result -= (parameter[i]-1) * H(parameter, arg).hold();
1320 if (lastentry < parameter.nops()) {
1321 result = result / (parameter.nops()-lastentry+1);
1322 return result.map(*this);
1334 // recursively call convert_from_RV on expression
1335 struct map_trafo_H_convert : public map_function
1337 ex operator()(const ex& e)
1339 if (is_a<add>(e) || is_a<mul>(e) || is_a<power>(e)) {
1340 return e.map(*this);
1342 if (is_a<function>(e)) {
1343 std::string name = ex_to<function>(e).get_name();
1345 lst parameter = ex_to<lst>(e.op(0));
1347 return convert_from_RV(parameter, arg);
1355 // translate notation from nested sums to Remiddi/Vermaseren
1356 lst convert_to_RV(const lst& o)
1359 for (lst::const_iterator it = o.begin(); it != o.end(); it++) {
1360 for (ex i=0; i<(*it)-1; i++) {
1369 // translate notation from Remiddi/Vermaseren to nested sums
1370 ex convert_from_RV(const lst& parameterlst, const ex& arg)
1372 lst newparameterlst;
1374 lst::const_iterator it = parameterlst.begin();
1376 while (it != parameterlst.end()) {
1380 newparameterlst.append((*it>0) ? count : -count);
1385 for (int i=1; i<count; i++) {
1386 newparameterlst.append(0);
1389 map_trafo_H_reduce_trailing_zeros filter;
1390 return filter(H(newparameterlst, arg).hold());
1394 // do the actual summation.
1395 cln::cl_N H_do_sum(const std::vector<int>& s, const cln::cl_N& x)
1397 const int j = s.size();
1399 std::vector<cln::cl_N> t(j);
1401 cln::cl_F one = cln::cl_float(1, cln::float_format(Digits));
1402 cln::cl_N factor = cln::expt(x, j) * one;
1408 t[j-1] = t[j-1] + 1 / cln::expt(cln::cl_I(q),s[j-1]);
1409 for (int k=j-2; k>=1; k--) {
1410 t[k] = t[k] + t[k+1] / cln::expt(cln::cl_I(q+j-1-k), s[k]);
1412 t[0] = t[0] + t[1] * factor / cln::expt(cln::cl_I(q+j-1), s[0]);
1413 factor = factor * x;
1414 } while (t[0] != t0buf);
1420 } // end of anonymous namespace
1423 //////////////////////////////////////////////////////////////////////
1425 // Harmonic polylogarithm H(m,x)
1429 //////////////////////////////////////////////////////////////////////
1432 static ex H_eval(const ex& x1, const ex& x2)
1440 if (x1.nops() == 1) {
1441 return Li(x1.op(0), x2);
1443 if (x2.info(info_flags::numeric) && (!x2.info(info_flags::crational))) {
1444 return H(x1,x2).evalf();
1446 return H(x1,x2).hold();
1450 static ex H_evalf(const ex& x1, const ex& x2)
1452 if (is_a<lst>(x1) && is_a<numeric>(x2)) {
1453 for (int i=0; i<x1.nops(); i++) {
1454 if (!x1.op(i).info(info_flags::posint)) {
1455 return H(x1,x2).hold();
1458 if (x1.nops() < 1) {
1461 if (x1.nops() == 1) {
1462 return Li(x1.op(0), x2).evalf();
1464 cln::cl_N x = ex_to<numeric>(x2).to_cl_N();
1466 return zeta(x1).evalf();
1470 if (cln::abs(x) > 1) {
1471 symbol xtemp("xtemp");
1472 map_trafo_H_1overx trafo;
1473 ex res = trafo(H(convert_to_RV(ex_to<lst>(x1)), xtemp));
1474 map_trafo_H_convert converter;
1475 res = converter(res);
1476 return res.subs(xtemp==x2).evalf();
1479 // since the x->1-x transformation produces a lot of terms, it is only
1480 // efficient for argument near one.
1481 if (cln::realpart(x) > 0.95) {
1482 symbol xtemp("xtemp");
1483 map_trafo_H_1mx trafo;
1484 ex res = trafo(H(convert_to_RV(ex_to<lst>(x1)), xtemp));
1485 map_trafo_H_convert converter;
1486 res = converter(res);
1487 return res.subs(xtemp==x2).evalf();
1490 // no trafo -> do summation
1491 int count = x1.nops();
1492 std::vector<int> r(count);
1493 for (int i=0; i<count; i++) {
1494 r[i] = ex_to<numeric>(x1.op(i)).to_int();
1497 return numeric(H_do_sum(r,x));
1500 return H(x1,x2).hold();
1504 static ex H_series(const ex& x1, const ex& x2, const relational& rel, int order, unsigned options)
1507 seq.push_back(expair(H(x1,x2), 0));
1508 return pseries(rel,seq);
1512 static ex H_deriv(const ex& x1, const ex& x2, unsigned deriv_param)
1514 GINAC_ASSERT(deriv_param < 2);
1515 if (deriv_param == 0) {
1518 if (is_a<lst>(x1)) {
1519 lst newparameter = ex_to<lst>(x1);
1520 if (x1.op(0) == 1) {
1521 newparameter.remove_first();
1522 return 1/(1-x2) * H(newparameter, x2);
1525 return H(newparameter, x2).hold() / x2;
1531 return H(x1-1, x2).hold() / x2;
1537 REGISTER_FUNCTION(H,
1539 evalf_func(H_evalf).
1540 do_not_evalf_params().
1541 series_func(H_series).
1542 derivative_func(H_deriv));
1545 //////////////////////////////////////////////////////////////////////
1547 // Multiple zeta values zeta(x) and zeta(x,s)
1551 //////////////////////////////////////////////////////////////////////
1554 // anonymous namespace for helper functions
1558 // parameters and data for [Cra] algorithm
1559 const cln::cl_N lambda = cln::cl_N("319/320");
1562 std::vector<std::vector<cln::cl_N> > f_kj;
1563 std::vector<cln::cl_N> crB;
1564 std::vector<std::vector<cln::cl_N> > crG;
1565 std::vector<cln::cl_N> crX;
1568 void halfcyclic_convolute(const std::vector<cln::cl_N>& a, const std::vector<cln::cl_N>& b, std::vector<cln::cl_N>& c)
1570 const int size = a.size();
1571 for (int n=0; n<size; n++) {
1573 for (int m=0; m<=n; m++) {
1574 c[n] = c[n] + a[m]*b[n-m];
1581 void initcX(const std::vector<int>& s)
1583 const int k = s.size();
1589 for (int i=0; i<=L2; i++) {
1590 crB.push_back(bernoulli(i).to_cl_N() / cln::factorial(i));
1595 for (int m=0; m<k-1; m++) {
1596 std::vector<cln::cl_N> crGbuf;
1599 for (int i=0; i<=L2; i++) {
1600 crGbuf.push_back(cln::factorial(i + Sm - m - 2) / cln::factorial(i + Smp1 - m - 2));
1602 crG.push_back(crGbuf);
1607 for (int m=0; m<k-1; m++) {
1608 std::vector<cln::cl_N> Xbuf;
1609 for (int i=0; i<=L2; i++) {
1610 Xbuf.push_back(crX[i] * crG[m][i]);
1612 halfcyclic_convolute(Xbuf, crB, crX);
1618 cln::cl_N crandall_Y_loop(const cln::cl_N& Sqk)
1620 cln::cl_F one = cln::cl_float(1, cln::float_format(Digits));
1621 cln::cl_N factor = cln::expt(lambda, Sqk);
1622 cln::cl_N res = factor / Sqk * crX[0] * one;
1627 factor = factor * lambda;
1629 res = res + crX[N] * factor / (N+Sqk);
1630 } while ((res != resbuf) || cln::zerop(crX[N]));
1636 void calc_f(int maxr)
1641 cln::cl_N t0, t1, t2, t3, t4;
1643 std::vector<std::vector<cln::cl_N> >::iterator it = f_kj.begin();
1644 cln::cl_F one = cln::cl_float(1, cln::float_format(Digits));
1646 t0 = cln::exp(-lambda);
1648 for (k=1; k<=L1; k++) {
1651 for (j=1; j<=maxr; j++) {
1654 for (i=2; i<=j; i++) {
1658 (*it).push_back(t2 * t3 * cln::expt(cln::cl_I(k),-j) * one);
1666 cln::cl_N crandall_Z(const std::vector<int>& s)
1668 const int j = s.size();
1677 t0 = t0 + f_kj[q+j-2][s[0]-1];
1678 } while (t0 != t0buf);
1680 return t0 / cln::factorial(s[0]-1);
1683 std::vector<cln::cl_N> t(j);
1690 t[j-1] = t[j-1] + 1 / cln::expt(cln::cl_I(q),s[j-1]);
1691 for (int k=j-2; k>=1; k--) {
1692 t[k] = t[k] + t[k+1] / cln::expt(cln::cl_I(q+j-1-k), s[k]);
1694 t[0] = t[0] + t[1] * f_kj[q+j-2][s[0]-1];
1695 } while (t[0] != t0buf);
1697 return t[0] / cln::factorial(s[0]-1);
1702 cln::cl_N zeta_do_sum_Crandall(const std::vector<int>& s)
1704 std::vector<int> r = s;
1705 const int j = r.size();
1707 // decide on maximal size of f_kj for crandall_Z
1711 L1 = Digits * 3 + j*2;
1714 // decide on maximal size of crX for crandall_Y
1717 } else if (Digits < 86) {
1719 } else if (Digits < 192) {
1721 } else if (Digits < 394) {
1723 } else if (Digits < 808) {
1733 for (int i=0; i<j; i++) {
1742 const cln::cl_N r0factorial = cln::factorial(r[0]-1);
1744 std::vector<int> rz;
1747 for (int k=r.size()-1; k>0; k--) {
1749 rz.insert(rz.begin(), r.back());
1750 skp1buf = rz.front();
1756 for (int q=0; q<skp1buf; q++) {
1758 cln::cl_N pp1 = crandall_Y_loop(Srun+q-k);
1759 cln::cl_N pp2 = crandall_Z(rz);
1764 res = res - pp1 * pp2 / cln::factorial(q);
1766 res = res + pp1 * pp2 / cln::factorial(q);
1769 rz.front() = skp1buf;
1771 rz.insert(rz.begin(), r.back());
1775 res = (res + crandall_Y_loop(S-j)) / r0factorial + crandall_Z(rz);
1781 cln::cl_N zeta_do_sum_simple(const std::vector<int>& r)
1783 const int j = r.size();
1785 // buffer for subsums
1786 std::vector<cln::cl_N> t(j);
1787 cln::cl_F one = cln::cl_float(1, cln::float_format(Digits));
1794 t[j-1] = t[j-1] + one / cln::expt(cln::cl_I(q),r[j-1]);
1795 for (int k=j-2; k>=0; k--) {
1796 t[k] = t[k] + one * t[k+1] / cln::expt(cln::cl_I(q+j-1-k), r[k]);
1798 } while (t[0] != t0buf);
1804 // does Hoelder convolution. see [BBB] (7.0)
1805 cln::cl_N zeta_do_Hoelder_convolution(const std::vector<int>& m_, const std::vector<int>& s_)
1807 // prepare parameters
1808 // holds Li arguments in [BBB] notation
1809 std::vector<int> s = s_;
1810 std::vector<int> m_p = m_;
1811 std::vector<int> m_q;
1812 // holds Li arguments in nested sums notation
1813 std::vector<cln::cl_N> s_p(s.size(), cln::cl_N(1));
1814 s_p[0] = s_p[0] * cln::cl_N("1/2");
1815 // convert notations
1817 for (int i=0; i<s_.size(); i++) {
1822 s[i] = sig * std::abs(s[i]);
1824 std::vector<cln::cl_N> s_q;
1825 cln::cl_N signum = 1;
1828 cln::cl_N res = multipleLi_do_sum(m_p, s_p);
1833 // change parameters
1834 if (s.front() > 0) {
1835 if (m_p.front() == 1) {
1836 m_p.erase(m_p.begin());
1837 s_p.erase(s_p.begin());
1838 if (s_p.size() > 0) {
1839 s_p.front() = s_p.front() * cln::cl_N("1/2");
1845 m_q.insert(m_q.begin(), 1);
1846 if (s_q.size() > 0) {
1847 s_q.front() = s_q.front() * 2;
1849 s_q.insert(s_q.begin(), cln::cl_N("1/2"));
1852 if (m_p.front() == 1) {
1853 m_p.erase(m_p.begin());
1854 s_p.erase(s_p.begin());
1855 if (s_p.size() > 0) {
1856 s_p.front() = s_p.front() * cln::cl_N("1/2");
1859 for (int i=0; i<s.size(); i++) {
1861 if (s[i] > 0) break;
1864 m_q.insert(m_q.begin(), 1);
1865 if (s_q.size() > 0) {
1866 s_q.front() = s_q.front() * 4;
1868 s_q.insert(s_q.begin(), cln::cl_N("1/4"));
1872 m_q.insert(m_q.begin(), 1);
1873 if (s_q.size() > 0) {
1874 s_q.front() = s_q.front() * 2;
1876 s_q.insert(s_q.begin(), cln::cl_N("1/2"));
1881 if (m_p.size() == 0) break;
1883 res = res + signum * multipleLi_do_sum(m_p, s_p) * multipleLi_do_sum(m_q, s_q);
1888 res = res + signum * multipleLi_do_sum(m_q, s_q);
1894 } // end of anonymous namespace
1897 //////////////////////////////////////////////////////////////////////
1899 // Multiple zeta values zeta(x)
1903 //////////////////////////////////////////////////////////////////////
1906 static ex zeta1_evalf(const ex& x)
1908 if (is_exactly_a<lst>(x) && (x.nops()>1)) {
1910 // multiple zeta value
1911 const int count = x.nops();
1912 const lst& xlst = ex_to<lst>(x);
1913 std::vector<int> r(count);
1915 // check parameters and convert them
1916 lst::const_iterator it1 = xlst.begin();
1917 std::vector<int>::iterator it2 = r.begin();
1919 if (!(*it1).info(info_flags::posint)) {
1920 return zeta(x).hold();
1922 *it2 = ex_to<numeric>(*it1).to_int();
1925 } while (it2 != r.end());
1927 // check for divergence
1929 return zeta(x).hold();
1932 // decide on summation algorithm
1933 // this is still a bit clumsy
1934 int limit = (Digits>17) ? 10 : 6;
1935 if ((r[0] < limit) || ((count > 3) && (r[1] < limit/2))) {
1936 return numeric(zeta_do_sum_Crandall(r));
1938 return numeric(zeta_do_sum_simple(r));
1942 // single zeta value
1943 if (is_exactly_a<numeric>(x) && (x != 1)) {
1945 return zeta(ex_to<numeric>(x));
1946 } catch (const dunno &e) { }
1949 return zeta(x).hold();
1953 static ex zeta1_eval(const ex& x)
1955 if (is_exactly_a<lst>(x)) {
1956 if (x.nops() == 1) {
1957 return zeta(x.op(0));
1959 return zeta(x).hold();
1962 if (x.info(info_flags::numeric)) {
1963 const numeric& y = ex_to<numeric>(x);
1964 // trap integer arguments:
1965 if (y.is_integer()) {
1969 if (y.is_equal(_num1)) {
1970 return zeta(x).hold();
1972 if (y.info(info_flags::posint)) {
1973 if (y.info(info_flags::odd)) {
1974 return zeta(x).hold();
1976 return abs(bernoulli(y)) * pow(Pi, y) * pow(_num2, y-_num1) / factorial(y);
1979 if (y.info(info_flags::odd)) {
1980 return -bernoulli(_num1-y) / (_num1-y);
1987 if (y.info(info_flags::numeric) && !y.info(info_flags::crational))
1988 return zeta1_evalf(x);
1990 return zeta(x).hold();
1994 static ex zeta1_deriv(const ex& x, unsigned deriv_param)
1996 GINAC_ASSERT(deriv_param==0);
1998 if (is_exactly_a<lst>(x)) {
2001 return zeta(_ex1, x);
2006 unsigned zeta1_SERIAL::serial =
2007 function::register_new(function_options("zeta").
2008 eval_func(zeta1_eval).
2009 evalf_func(zeta1_evalf).
2010 do_not_evalf_params().
2011 derivative_func(zeta1_deriv).
2012 latex_name("\\zeta").
2016 //////////////////////////////////////////////////////////////////////
2018 // Alternating Euler sum zeta(x,s)
2022 //////////////////////////////////////////////////////////////////////
2025 static ex zeta2_evalf(const ex& x, const ex& s)
2027 if (is_exactly_a<lst>(x)) {
2029 // alternating Euler sum
2030 const int count = x.nops();
2031 const lst& xlst = ex_to<lst>(x);
2032 const lst& slst = ex_to<lst>(s);
2033 std::vector<int> xi(count);
2034 std::vector<int> si(count);
2036 // check parameters and convert them
2037 lst::const_iterator it_xread = xlst.begin();
2038 lst::const_iterator it_sread = slst.begin();
2039 std::vector<int>::iterator it_xwrite = xi.begin();
2040 std::vector<int>::iterator it_swrite = si.begin();
2042 if (!(*it_xread).info(info_flags::posint)) {
2043 return zeta(x, s).hold();
2045 *it_xwrite = ex_to<numeric>(*it_xread).to_int();
2046 if (*it_sread > 0) {
2055 } while (it_xwrite != xi.end());
2057 // check for divergence
2058 if ((xi[0] == 1) && (si[0] == 1)) {
2059 return zeta(x, s).hold();
2062 // use Hoelder convolution
2063 return numeric(zeta_do_Hoelder_convolution(xi, si));
2066 return zeta(x, s).hold();
2070 static ex zeta2_eval(const ex& x, const ex& s)
2072 if (is_exactly_a<lst>(s)) {
2073 const lst& l = ex_to<lst>(s);
2074 lst::const_iterator it = l.begin();
2075 while (it != l.end()) {
2076 if ((*it).info(info_flags::negative)) {
2077 return zeta(x, s).hold();
2083 if (s.info(info_flags::positive)) {
2088 return zeta(x, s).hold();
2092 static ex zeta2_deriv(const ex& x, const ex& s, unsigned deriv_param)
2094 GINAC_ASSERT(deriv_param==0);
2096 if (is_exactly_a<lst>(x)) {
2099 if ((is_exactly_a<lst>(s) && (s.op(0) > 0)) || (s > 0)) {
2100 return zeta(_ex1, x);
2107 unsigned zeta2_SERIAL::serial =
2108 function::register_new(function_options("zeta").
2109 eval_func(zeta2_eval).
2110 evalf_func(zeta2_evalf).
2111 do_not_evalf_params().
2112 derivative_func(zeta2_deriv).
2113 latex_name("\\zeta").
2117 } // namespace GiNaC