3 * This file implements several functions that work on univariate and
4 * multivariate polynomials and rational functions.
5 * These functions include polynomial quotient and remainder, GCD and LCM
6 * computation, square-free factorization and rational function normalization. */
9 * GiNaC Copyright (C) 1999-2000 Johannes Gutenberg University Mainz, Germany
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License as published by
13 * the Free Software Foundation; either version 2 of the License, or
14 * (at your option) any later version.
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 * GNU General Public License for more details.
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software
23 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
35 #include "expairseq.h"
44 #include "relational.h"
49 #ifndef NO_NAMESPACE_GINAC
51 #endif // ndef NO_NAMESPACE_GINAC
53 // If comparing expressions (ex::compare()) is fast, you can set this to 1.
54 // Some routines like quo(), rem() and gcd() will then return a quick answer
55 // when they are called with two identical arguments.
56 #define FAST_COMPARE 1
58 // Set this if you want divide_in_z() to use remembering
59 #define USE_REMEMBER 0
61 // Set this if you want divide_in_z() to use trial division followed by
62 // polynomial interpolation (usually slower except for very large problems)
63 #define USE_TRIAL_DIVISION 0
65 // Set this to enable some statistical output for the GCD routines
70 // Statistics variables
71 static int gcd_called = 0;
72 static int sr_gcd_called = 0;
73 static int heur_gcd_called = 0;
74 static int heur_gcd_failed = 0;
76 // Print statistics at end of program
77 static struct _stat_print {
80 cout << "gcd() called " << gcd_called << " times\n";
81 cout << "sr_gcd() called " << sr_gcd_called << " times\n";
82 cout << "heur_gcd() called " << heur_gcd_called << " times\n";
83 cout << "heur_gcd() failed " << heur_gcd_failed << " times\n";
89 /** Return pointer to first symbol found in expression. Due to GiNaCĀ“s
90 * internal ordering of terms, it may not be obvious which symbol this
91 * function returns for a given expression.
93 * @param e expression to search
94 * @param x pointer to first symbol found (returned)
95 * @return "false" if no symbol was found, "true" otherwise */
96 static bool get_first_symbol(const ex &e, const symbol *&x)
98 if (is_ex_exactly_of_type(e, symbol)) {
99 x = static_cast<symbol *>(e.bp);
101 } else if (is_ex_exactly_of_type(e, add) || is_ex_exactly_of_type(e, mul)) {
102 for (unsigned i=0; i<e.nops(); i++)
103 if (get_first_symbol(e.op(i), x))
105 } else if (is_ex_exactly_of_type(e, power)) {
106 if (get_first_symbol(e.op(0), x))
114 * Statistical information about symbols in polynomials
117 /** This structure holds information about the highest and lowest degrees
118 * in which a symbol appears in two multivariate polynomials "a" and "b".
119 * A vector of these structures with information about all symbols in
120 * two polynomials can be created with the function get_symbol_stats().
122 * @see get_symbol_stats */
124 /** Pointer to symbol */
127 /** Highest degree of symbol in polynomial "a" */
130 /** Highest degree of symbol in polynomial "b" */
133 /** Lowest degree of symbol in polynomial "a" */
136 /** Lowest degree of symbol in polynomial "b" */
139 /** Maximum of deg_a and deg_b (Used for sorting) */
142 /** Commparison operator for sorting */
143 bool operator<(const sym_desc &x) const {return max_deg < x.max_deg;}
146 // Vector of sym_desc structures
147 typedef vector<sym_desc> sym_desc_vec;
149 // Add symbol the sym_desc_vec (used internally by get_symbol_stats())
150 static void add_symbol(const symbol *s, sym_desc_vec &v)
152 sym_desc_vec::iterator it = v.begin(), itend = v.end();
153 while (it != itend) {
154 if (it->sym->compare(*s) == 0) // If it's already in there, don't add it a second time
163 // Collect all symbols of an expression (used internally by get_symbol_stats())
164 static void collect_symbols(const ex &e, sym_desc_vec &v)
166 if (is_ex_exactly_of_type(e, symbol)) {
167 add_symbol(static_cast<symbol *>(e.bp), v);
168 } else if (is_ex_exactly_of_type(e, add) || is_ex_exactly_of_type(e, mul)) {
169 for (unsigned i=0; i<e.nops(); i++)
170 collect_symbols(e.op(i), v);
171 } else if (is_ex_exactly_of_type(e, power)) {
172 collect_symbols(e.op(0), v);
176 /** Collect statistical information about symbols in polynomials.
177 * This function fills in a vector of "sym_desc" structs which contain
178 * information about the highest and lowest degrees of all symbols that
179 * appear in two polynomials. The vector is then sorted by minimum
180 * degree (lowest to highest). The information gathered by this
181 * function is used by the GCD routines to identify trivial factors
182 * and to determine which variable to choose as the main variable
183 * for GCD computation.
185 * @param a first multivariate polynomial
186 * @param b second multivariate polynomial
187 * @param v vector of sym_desc structs (filled in) */
188 static void get_symbol_stats(const ex &a, const ex &b, sym_desc_vec &v)
190 collect_symbols(a.eval(), v); // eval() to expand assigned symbols
191 collect_symbols(b.eval(), v);
192 sym_desc_vec::iterator it = v.begin(), itend = v.end();
193 while (it != itend) {
194 int deg_a = a.degree(*(it->sym));
195 int deg_b = b.degree(*(it->sym));
198 it->max_deg = max(deg_a, deg_b);
199 it->ldeg_a = a.ldegree(*(it->sym));
200 it->ldeg_b = b.ldegree(*(it->sym));
203 sort(v.begin(), v.end());
205 clog << "Symbols:\n";
206 it = v.begin(); itend = v.end();
207 while (it != itend) {
208 clog << " " << *it->sym << ": deg_a=" << it->deg_a << ", deg_b=" << it->deg_b << ", ldeg_a=" << it->ldeg_a << ", ldeg_b=" << it->ldeg_b << ", max_deg=" << it->max_deg << endl;
209 clog << " lcoeff_a=" << a.lcoeff(*(it->sym)) << ", lcoeff_b=" << b.lcoeff(*(it->sym)) << endl;
217 * Computation of LCM of denominators of coefficients of a polynomial
220 // Compute LCM of denominators of coefficients by going through the
221 // expression recursively (used internally by lcm_of_coefficients_denominators())
222 static numeric lcmcoeff(const ex &e, const numeric &l)
224 if (e.info(info_flags::rational))
225 return lcm(ex_to_numeric(e).denom(), l);
226 else if (is_ex_exactly_of_type(e, add)) {
228 for (unsigned i=0; i<e.nops(); i++)
229 c = lcmcoeff(e.op(i), c);
231 } else if (is_ex_exactly_of_type(e, mul)) {
233 for (unsigned i=0; i<e.nops(); i++)
234 c *= lcmcoeff(e.op(i), _num1());
236 } else if (is_ex_exactly_of_type(e, power))
237 return pow(lcmcoeff(e.op(0), l), ex_to_numeric(e.op(1)));
241 /** Compute LCM of denominators of coefficients of a polynomial.
242 * Given a polynomial with rational coefficients, this function computes
243 * the LCM of the denominators of all coefficients. This can be used
244 * to bring a polynomial from Q[X] to Z[X].
246 * @param e multivariate polynomial (need not be expanded)
247 * @return LCM of denominators of coefficients */
248 static numeric lcm_of_coefficients_denominators(const ex &e)
250 return lcmcoeff(e, _num1());
253 /** Bring polynomial from Q[X] to Z[X] by multiplying in the previously
254 * determined LCM of the coefficient's denominators.
256 * @param e multivariate polynomial (need not be expanded)
257 * @param lcm LCM to multiply in */
258 static ex multiply_lcm(const ex &e, const numeric &lcm)
260 if (is_ex_exactly_of_type(e, mul)) {
262 numeric lcm_accum = _num1();
263 for (unsigned i=0; i<e.nops(); i++) {
264 numeric op_lcm = lcmcoeff(e.op(i), _num1());
265 c *= multiply_lcm(e.op(i), op_lcm);
268 c *= lcm / lcm_accum;
270 } else if (is_ex_exactly_of_type(e, add)) {
272 for (unsigned i=0; i<e.nops(); i++)
273 c += multiply_lcm(e.op(i), lcm);
275 } else if (is_ex_exactly_of_type(e, power)) {
276 return pow(multiply_lcm(e.op(0), lcm.power(ex_to_numeric(e.op(1)).inverse())), e.op(1));
282 /** Compute the integer content (= GCD of all numeric coefficients) of an
283 * expanded polynomial.
285 * @param e expanded polynomial
286 * @return integer content */
287 numeric ex::integer_content(void) const
290 return bp->integer_content();
293 numeric basic::integer_content(void) const
298 numeric numeric::integer_content(void) const
303 numeric add::integer_content(void) const
305 epvector::const_iterator it = seq.begin();
306 epvector::const_iterator itend = seq.end();
308 while (it != itend) {
309 GINAC_ASSERT(!is_ex_exactly_of_type(it->rest,numeric));
310 GINAC_ASSERT(is_ex_exactly_of_type(it->coeff,numeric));
311 c = gcd(ex_to_numeric(it->coeff), c);
314 GINAC_ASSERT(is_ex_exactly_of_type(overall_coeff,numeric));
315 c = gcd(ex_to_numeric(overall_coeff),c);
319 numeric mul::integer_content(void) const
321 #ifdef DO_GINAC_ASSERT
322 epvector::const_iterator it = seq.begin();
323 epvector::const_iterator itend = seq.end();
324 while (it != itend) {
325 GINAC_ASSERT(!is_ex_exactly_of_type(recombine_pair_to_ex(*it),numeric));
328 #endif // def DO_GINAC_ASSERT
329 GINAC_ASSERT(is_ex_exactly_of_type(overall_coeff,numeric));
330 return abs(ex_to_numeric(overall_coeff));
335 * Polynomial quotients and remainders
338 /** Quotient q(x) of polynomials a(x) and b(x) in Q[x].
339 * It satisfies a(x)=b(x)*q(x)+r(x).
341 * @param a first polynomial in x (dividend)
342 * @param b second polynomial in x (divisor)
343 * @param x a and b are polynomials in x
344 * @param check_args check whether a and b are polynomials with rational
345 * coefficients (defaults to "true")
346 * @return quotient of a and b in Q[x] */
347 ex quo(const ex &a, const ex &b, const symbol &x, bool check_args)
350 throw(std::overflow_error("quo: division by zero"));
351 if (is_ex_exactly_of_type(a, numeric) && is_ex_exactly_of_type(b, numeric))
357 if (check_args && (!a.info(info_flags::rational_polynomial) || !b.info(info_flags::rational_polynomial)))
358 throw(std::invalid_argument("quo: arguments must be polynomials over the rationals"));
360 // Polynomial long division
365 int bdeg = b.degree(x);
366 int rdeg = r.degree(x);
367 ex blcoeff = b.expand().coeff(x, bdeg);
368 bool blcoeff_is_numeric = is_ex_exactly_of_type(blcoeff, numeric);
369 while (rdeg >= bdeg) {
370 ex term, rcoeff = r.coeff(x, rdeg);
371 if (blcoeff_is_numeric)
372 term = rcoeff / blcoeff;
374 if (!divide(rcoeff, blcoeff, term, false))
375 return *new ex(fail());
377 term *= power(x, rdeg - bdeg);
379 r -= (term * b).expand();
388 /** Remainder r(x) of polynomials a(x) and b(x) in Q[x].
389 * It satisfies a(x)=b(x)*q(x)+r(x).
391 * @param a first polynomial in x (dividend)
392 * @param b second polynomial in x (divisor)
393 * @param x a and b are polynomials in x
394 * @param check_args check whether a and b are polynomials with rational
395 * coefficients (defaults to "true")
396 * @return remainder of a(x) and b(x) in Q[x] */
397 ex rem(const ex &a, const ex &b, const symbol &x, bool check_args)
400 throw(std::overflow_error("rem: division by zero"));
401 if (is_ex_exactly_of_type(a, numeric)) {
402 if (is_ex_exactly_of_type(b, numeric))
411 if (check_args && (!a.info(info_flags::rational_polynomial) || !b.info(info_flags::rational_polynomial)))
412 throw(std::invalid_argument("rem: arguments must be polynomials over the rationals"));
414 // Polynomial long division
418 int bdeg = b.degree(x);
419 int rdeg = r.degree(x);
420 ex blcoeff = b.expand().coeff(x, bdeg);
421 bool blcoeff_is_numeric = is_ex_exactly_of_type(blcoeff, numeric);
422 while (rdeg >= bdeg) {
423 ex term, rcoeff = r.coeff(x, rdeg);
424 if (blcoeff_is_numeric)
425 term = rcoeff / blcoeff;
427 if (!divide(rcoeff, blcoeff, term, false))
428 return *new ex(fail());
430 term *= power(x, rdeg - bdeg);
431 r -= (term * b).expand();
440 /** Pseudo-remainder of polynomials a(x) and b(x) in Z[x].
442 * @param a first polynomial in x (dividend)
443 * @param b second polynomial in x (divisor)
444 * @param x a and b are polynomials in x
445 * @param check_args check whether a and b are polynomials with rational
446 * coefficients (defaults to "true")
447 * @return pseudo-remainder of a(x) and b(x) in Z[x] */
448 ex prem(const ex &a, const ex &b, const symbol &x, bool check_args)
451 throw(std::overflow_error("prem: division by zero"));
452 if (is_ex_exactly_of_type(a, numeric)) {
453 if (is_ex_exactly_of_type(b, numeric))
458 if (check_args && (!a.info(info_flags::rational_polynomial) || !b.info(info_flags::rational_polynomial)))
459 throw(std::invalid_argument("prem: arguments must be polynomials over the rationals"));
461 // Polynomial long division
464 int rdeg = r.degree(x);
465 int bdeg = eb.degree(x);
468 blcoeff = eb.coeff(x, bdeg);
472 eb -= blcoeff * power(x, bdeg);
476 int delta = rdeg - bdeg + 1, i = 0;
477 while (rdeg >= bdeg && !r.is_zero()) {
478 ex rlcoeff = r.coeff(x, rdeg);
479 ex term = (power(x, rdeg - bdeg) * eb * rlcoeff).expand();
483 r -= rlcoeff * power(x, rdeg);
484 r = (blcoeff * r).expand() - term;
488 return power(blcoeff, delta - i) * r;
492 /** Exact polynomial division of a(X) by b(X) in Q[X].
494 * @param a first multivariate polynomial (dividend)
495 * @param b second multivariate polynomial (divisor)
496 * @param q quotient (returned)
497 * @param check_args check whether a and b are polynomials with rational
498 * coefficients (defaults to "true")
499 * @return "true" when exact division succeeds (quotient returned in q),
500 * "false" otherwise */
501 bool divide(const ex &a, const ex &b, ex &q, bool check_args)
505 throw(std::overflow_error("divide: division by zero"));
508 if (is_ex_exactly_of_type(b, numeric)) {
511 } else if (is_ex_exactly_of_type(a, numeric))
519 if (check_args && (!a.info(info_flags::rational_polynomial) || !b.info(info_flags::rational_polynomial)))
520 throw(std::invalid_argument("divide: arguments must be polynomials over the rationals"));
524 if (!get_first_symbol(a, x) && !get_first_symbol(b, x))
525 throw(std::invalid_argument("invalid expression in divide()"));
527 // Polynomial long division (recursive)
531 int bdeg = b.degree(*x);
532 int rdeg = r.degree(*x);
533 ex blcoeff = b.expand().coeff(*x, bdeg);
534 bool blcoeff_is_numeric = is_ex_exactly_of_type(blcoeff, numeric);
535 while (rdeg >= bdeg) {
536 ex term, rcoeff = r.coeff(*x, rdeg);
537 if (blcoeff_is_numeric)
538 term = rcoeff / blcoeff;
540 if (!divide(rcoeff, blcoeff, term, false))
542 term *= power(*x, rdeg - bdeg);
544 r -= (term * b).expand();
558 typedef pair<ex, ex> ex2;
559 typedef pair<ex, bool> exbool;
562 bool operator() (const ex2 p, const ex2 q) const
564 return p.first.compare(q.first) < 0 || (!(q.first.compare(p.first) < 0) && p.second.compare(q.second) < 0);
568 typedef map<ex2, exbool, ex2_less> ex2_exbool_remember;
572 /** Exact polynomial division of a(X) by b(X) in Z[X].
573 * This functions works like divide() but the input and output polynomials are
574 * in Z[X] instead of Q[X] (i.e. they have integer coefficients). Unlike
575 * divide(), it doesnĀ“t check whether the input polynomials really are integer
576 * polynomials, so be careful of what you pass in. Also, you have to run
577 * get_symbol_stats() over the input polynomials before calling this function
578 * and pass an iterator to the first element of the sym_desc vector. This
579 * function is used internally by the heur_gcd().
581 * @param a first multivariate polynomial (dividend)
582 * @param b second multivariate polynomial (divisor)
583 * @param q quotient (returned)
584 * @param var iterator to first element of vector of sym_desc structs
585 * @return "true" when exact division succeeds (the quotient is returned in
586 * q), "false" otherwise.
587 * @see get_symbol_stats, heur_gcd */
588 static bool divide_in_z(const ex &a, const ex &b, ex &q, sym_desc_vec::const_iterator var)
592 throw(std::overflow_error("divide_in_z: division by zero"));
593 if (b.is_equal(_ex1())) {
597 if (is_ex_exactly_of_type(a, numeric)) {
598 if (is_ex_exactly_of_type(b, numeric)) {
600 return q.info(info_flags::integer);
613 static ex2_exbool_remember dr_remember;
614 ex2_exbool_remember::const_iterator remembered = dr_remember.find(ex2(a, b));
615 if (remembered != dr_remember.end()) {
616 q = remembered->second.first;
617 return remembered->second.second;
622 const symbol *x = var->sym;
625 int adeg = a.degree(*x), bdeg = b.degree(*x);
629 #if USE_TRIAL_DIVISION
631 // Trial division with polynomial interpolation
634 // Compute values at evaluation points 0..adeg
635 vector<numeric> alpha; alpha.reserve(adeg + 1);
636 exvector u; u.reserve(adeg + 1);
637 numeric point = _num0();
639 for (i=0; i<=adeg; i++) {
640 ex bs = b.subs(*x == point);
641 while (bs.is_zero()) {
643 bs = b.subs(*x == point);
645 if (!divide_in_z(a.subs(*x == point), bs, c, var+1))
647 alpha.push_back(point);
653 vector<numeric> rcp; rcp.reserve(adeg + 1);
654 rcp.push_back(_num0());
655 for (k=1; k<=adeg; k++) {
656 numeric product = alpha[k] - alpha[0];
658 product *= alpha[k] - alpha[i];
659 rcp.push_back(product.inverse());
662 // Compute Newton coefficients
663 exvector v; v.reserve(adeg + 1);
665 for (k=1; k<=adeg; k++) {
667 for (i=k-2; i>=0; i--)
668 temp = temp * (alpha[k] - alpha[i]) + v[i];
669 v.push_back((u[k] - temp) * rcp[k]);
672 // Convert from Newton form to standard form
674 for (k=adeg-1; k>=0; k--)
675 c = c * (*x - alpha[k]) + v[k];
677 if (c.degree(*x) == (adeg - bdeg)) {
685 // Polynomial long division (recursive)
691 ex blcoeff = eb.coeff(*x, bdeg);
692 while (rdeg >= bdeg) {
693 ex term, rcoeff = r.coeff(*x, rdeg);
694 if (!divide_in_z(rcoeff, blcoeff, term, var+1))
696 term = (term * power(*x, rdeg - bdeg)).expand();
698 r -= (term * eb).expand();
701 dr_remember[ex2(a, b)] = exbool(q, true);
708 dr_remember[ex2(a, b)] = exbool(q, false);
717 * Separation of unit part, content part and primitive part of polynomials
720 /** Compute unit part (= sign of leading coefficient) of a multivariate
721 * polynomial in Z[x]. The product of unit part, content part, and primitive
722 * part is the polynomial itself.
724 * @param x variable in which to compute the unit part
726 * @see ex::content, ex::primpart */
727 ex ex::unit(const symbol &x) const
729 ex c = expand().lcoeff(x);
730 if (is_ex_exactly_of_type(c, numeric))
731 return c < _ex0() ? _ex_1() : _ex1();
734 if (get_first_symbol(c, y))
737 throw(std::invalid_argument("invalid expression in unit()"));
742 /** Compute content part (= unit normal GCD of all coefficients) of a
743 * multivariate polynomial in Z[x]. The product of unit part, content part,
744 * and primitive part is the polynomial itself.
746 * @param x variable in which to compute the content part
747 * @return content part
748 * @see ex::unit, ex::primpart */
749 ex ex::content(const symbol &x) const
753 if (is_ex_exactly_of_type(*this, numeric))
754 return info(info_flags::negative) ? -*this : *this;
759 // First, try the integer content
760 ex c = e.integer_content();
762 ex lcoeff = r.lcoeff(x);
763 if (lcoeff.info(info_flags::integer))
766 // GCD of all coefficients
767 int deg = e.degree(x);
768 int ldeg = e.ldegree(x);
770 return e.lcoeff(x) / e.unit(x);
772 for (int i=ldeg; i<=deg; i++)
773 c = gcd(e.coeff(x, i), c, NULL, NULL, false);
778 /** Compute primitive part of a multivariate polynomial in Z[x].
779 * The product of unit part, content part, and primitive part is the
782 * @param x variable in which to compute the primitive part
783 * @return primitive part
784 * @see ex::unit, ex::content */
785 ex ex::primpart(const symbol &x) const
789 if (is_ex_exactly_of_type(*this, numeric))
796 if (is_ex_exactly_of_type(c, numeric))
797 return *this / (c * u);
799 return quo(*this, c * u, x, false);
803 /** Compute primitive part of a multivariate polynomial in Z[x] when the
804 * content part is already known. This function is faster in computing the
805 * primitive part than the previous function.
807 * @param x variable in which to compute the primitive part
808 * @param c previously computed content part
809 * @return primitive part */
810 ex ex::primpart(const symbol &x, const ex &c) const
816 if (is_ex_exactly_of_type(*this, numeric))
820 if (is_ex_exactly_of_type(c, numeric))
821 return *this / (c * u);
823 return quo(*this, c * u, x, false);
828 * GCD of multivariate polynomials
831 /** Compute GCD of multivariate polynomials using the Euclidean PRS algorithm
832 * (not really suited for multivariate GCDs). This function is only provided
833 * for testing purposes.
835 * @param a first multivariate polynomial
836 * @param b second multivariate polynomial
837 * @param x pointer to symbol (main variable) in which to compute the GCD in
838 * @return the GCD as a new expression
841 static ex eu_gcd(const ex &a, const ex &b, const symbol *x)
843 //clog << "eu_gcd(" << a << "," << b << ")\n";
845 // Sort c and d so that c has higher degree
847 int adeg = a.degree(*x), bdeg = b.degree(*x);
856 // Euclidean algorithm
859 //clog << " d = " << d << endl;
860 r = rem(c, d, *x, false);
862 return d.primpart(*x);
869 /** Compute GCD of multivariate polynomials using the Euclidean PRS algorithm
870 * with pseudo-remainders ("World's Worst GCD Algorithm", staying in Z[X]).
871 * This function is only provided for testing purposes.
873 * @param a first multivariate polynomial
874 * @param b second multivariate polynomial
875 * @param x pointer to symbol (main variable) in which to compute the GCD in
876 * @return the GCD as a new expression
879 static ex euprem_gcd(const ex &a, const ex &b, const symbol *x)
881 //clog << "euprem_gcd(" << a << "," << b << ")\n";
883 // Sort c and d so that c has higher degree
885 int adeg = a.degree(*x), bdeg = b.degree(*x);
894 // Euclidean algorithm with pseudo-remainders
897 //clog << " d = " << d << endl;
898 r = prem(c, d, *x, false);
900 return d.primpart(*x);
907 /** Compute GCD of multivariate polynomials using the primitive Euclidean
908 * PRS algorithm (complete content removal at each step). This function is
909 * only provided for testing purposes.
911 * @param a first multivariate polynomial
912 * @param b second multivariate polynomial
913 * @param x pointer to symbol (main variable) in which to compute the GCD in
914 * @return the GCD as a new expression
917 static ex peu_gcd(const ex &a, const ex &b, const symbol *x)
919 //clog << "peu_gcd(" << a << "," << b << ")\n";
921 // Sort c and d so that c has higher degree
923 int adeg = a.degree(*x), bdeg = b.degree(*x);
935 // Remove content from c and d, to be attached to GCD later
936 ex cont_c = c.content(*x);
937 ex cont_d = d.content(*x);
938 ex gamma = gcd(cont_c, cont_d, NULL, NULL, false);
941 c = c.primpart(*x, cont_c);
942 d = d.primpart(*x, cont_d);
944 // Euclidean algorithm with content removal
947 //clog << " d = " << d << endl;
948 r = prem(c, d, *x, false);
957 /** Compute GCD of multivariate polynomials using the reduced PRS algorithm.
958 * This function is only provided for testing purposes.
960 * @param a first multivariate polynomial
961 * @param b second multivariate polynomial
962 * @param x pointer to symbol (main variable) in which to compute the GCD in
963 * @return the GCD as a new expression
966 static ex red_gcd(const ex &a, const ex &b, const symbol *x)
968 //clog << "red_gcd(" << a << "," << b << ")\n";
970 // Sort c and d so that c has higher degree
972 int adeg = a.degree(*x), bdeg = b.degree(*x);
986 // Remove content from c and d, to be attached to GCD later
987 ex cont_c = c.content(*x);
988 ex cont_d = d.content(*x);
989 ex gamma = gcd(cont_c, cont_d, NULL, NULL, false);
992 c = c.primpart(*x, cont_c);
993 d = d.primpart(*x, cont_d);
995 // First element of subresultant sequence
997 int delta = cdeg - ddeg;
1000 // Calculate polynomial pseudo-remainder
1001 //clog << " d = " << d << endl;
1002 r = prem(c, d, *x, false);
1004 return gamma * d.primpart(*x);
1008 if (!divide(r, pow(ri, delta), d, false))
1009 throw(std::runtime_error("invalid expression in red_gcd(), division failed"));
1010 ddeg = d.degree(*x);
1012 if (is_ex_exactly_of_type(r, numeric))
1015 return gamma * r.primpart(*x);
1018 ri = c.expand().lcoeff(*x);
1019 delta = cdeg - ddeg;
1024 /** Compute GCD of multivariate polynomials using the subresultant PRS
1025 * algorithm. This function is used internally by gcd().
1027 * @param a first multivariate polynomial
1028 * @param b second multivariate polynomial
1029 * @param x pointer to symbol (main variable) in which to compute the GCD in
1030 * @return the GCD as a new expression
1032 static ex sr_gcd(const ex &a, const ex &b, const symbol *x)
1034 //clog << "sr_gcd(" << a << "," << b << ")\n";
1039 // Sort c and d so that c has higher degree
1041 int adeg = a.degree(*x), bdeg = b.degree(*x);
1055 // Remove content from c and d, to be attached to GCD later
1056 ex cont_c = c.content(*x);
1057 ex cont_d = d.content(*x);
1058 ex gamma = gcd(cont_c, cont_d, NULL, NULL, false);
1061 c = c.primpart(*x, cont_c);
1062 d = d.primpart(*x, cont_d);
1063 //clog << " content " << gamma << " removed, continuing with sr_gcd(" << c << "," << d << ")\n";
1065 // First element of subresultant sequence
1066 ex r = _ex0(), ri = _ex1(), psi = _ex1();
1067 int delta = cdeg - ddeg;
1070 // Calculate polynomial pseudo-remainder
1071 //clog << " start of loop, psi = " << psi << ", calculating pseudo-remainder...\n";
1072 //clog << " d = " << d << endl;
1073 r = prem(c, d, *x, false);
1075 return gamma * d.primpart(*x);
1078 //clog << " dividing...\n";
1079 if (!divide(r, ri * pow(psi, delta), d, false))
1080 throw(std::runtime_error("invalid expression in sr_gcd(), division failed"));
1081 ddeg = d.degree(*x);
1083 if (is_ex_exactly_of_type(r, numeric))
1086 return gamma * r.primpart(*x);
1089 // Next element of subresultant sequence
1090 //clog << " calculating next subresultant...\n";
1091 ri = c.expand().lcoeff(*x);
1095 divide(pow(ri, delta), pow(psi, delta-1), psi, false);
1096 delta = cdeg - ddeg;
1101 /** Return maximum (absolute value) coefficient of a polynomial.
1102 * This function is used internally by heur_gcd().
1104 * @param e expanded multivariate polynomial
1105 * @return maximum coefficient
1107 numeric ex::max_coefficient(void) const
1109 GINAC_ASSERT(bp!=0);
1110 return bp->max_coefficient();
1113 numeric basic::max_coefficient(void) const
1118 numeric numeric::max_coefficient(void) const
1123 numeric add::max_coefficient(void) const
1125 epvector::const_iterator it = seq.begin();
1126 epvector::const_iterator itend = seq.end();
1127 GINAC_ASSERT(is_ex_exactly_of_type(overall_coeff,numeric));
1128 numeric cur_max = abs(ex_to_numeric(overall_coeff));
1129 while (it != itend) {
1131 GINAC_ASSERT(!is_ex_exactly_of_type(it->rest,numeric));
1132 a = abs(ex_to_numeric(it->coeff));
1140 numeric mul::max_coefficient(void) const
1142 #ifdef DO_GINAC_ASSERT
1143 epvector::const_iterator it = seq.begin();
1144 epvector::const_iterator itend = seq.end();
1145 while (it != itend) {
1146 GINAC_ASSERT(!is_ex_exactly_of_type(recombine_pair_to_ex(*it),numeric));
1149 #endif // def DO_GINAC_ASSERT
1150 GINAC_ASSERT(is_ex_exactly_of_type(overall_coeff,numeric));
1151 return abs(ex_to_numeric(overall_coeff));
1155 /** Apply symmetric modular homomorphism to a multivariate polynomial.
1156 * This function is used internally by heur_gcd().
1158 * @param e expanded multivariate polynomial
1160 * @return mapped polynomial
1162 ex ex::smod(const numeric &xi) const
1164 GINAC_ASSERT(bp!=0);
1165 return bp->smod(xi);
1168 ex basic::smod(const numeric &xi) const
1173 ex numeric::smod(const numeric &xi) const
1175 #ifndef NO_NAMESPACE_GINAC
1176 return GiNaC::smod(*this, xi);
1177 #else // ndef NO_NAMESPACE_GINAC
1178 return ::smod(*this, xi);
1179 #endif // ndef NO_NAMESPACE_GINAC
1182 ex add::smod(const numeric &xi) const
1185 newseq.reserve(seq.size()+1);
1186 epvector::const_iterator it = seq.begin();
1187 epvector::const_iterator itend = seq.end();
1188 while (it != itend) {
1189 GINAC_ASSERT(!is_ex_exactly_of_type(it->rest,numeric));
1190 #ifndef NO_NAMESPACE_GINAC
1191 numeric coeff = GiNaC::smod(ex_to_numeric(it->coeff), xi);
1192 #else // ndef NO_NAMESPACE_GINAC
1193 numeric coeff = ::smod(ex_to_numeric(it->coeff), xi);
1194 #endif // ndef NO_NAMESPACE_GINAC
1195 if (!coeff.is_zero())
1196 newseq.push_back(expair(it->rest, coeff));
1199 GINAC_ASSERT(is_ex_exactly_of_type(overall_coeff,numeric));
1200 #ifndef NO_NAMESPACE_GINAC
1201 numeric coeff = GiNaC::smod(ex_to_numeric(overall_coeff), xi);
1202 #else // ndef NO_NAMESPACE_GINAC
1203 numeric coeff = ::smod(ex_to_numeric(overall_coeff), xi);
1204 #endif // ndef NO_NAMESPACE_GINAC
1205 return (new add(newseq,coeff))->setflag(status_flags::dynallocated);
1208 ex mul::smod(const numeric &xi) const
1210 #ifdef DO_GINAC_ASSERT
1211 epvector::const_iterator it = seq.begin();
1212 epvector::const_iterator itend = seq.end();
1213 while (it != itend) {
1214 GINAC_ASSERT(!is_ex_exactly_of_type(recombine_pair_to_ex(*it),numeric));
1217 #endif // def DO_GINAC_ASSERT
1218 mul * mulcopyp=new mul(*this);
1219 GINAC_ASSERT(is_ex_exactly_of_type(overall_coeff,numeric));
1220 #ifndef NO_NAMESPACE_GINAC
1221 mulcopyp->overall_coeff = GiNaC::smod(ex_to_numeric(overall_coeff),xi);
1222 #else // ndef NO_NAMESPACE_GINAC
1223 mulcopyp->overall_coeff = ::smod(ex_to_numeric(overall_coeff),xi);
1224 #endif // ndef NO_NAMESPACE_GINAC
1225 mulcopyp->clearflag(status_flags::evaluated);
1226 mulcopyp->clearflag(status_flags::hash_calculated);
1227 return mulcopyp->setflag(status_flags::dynallocated);
1231 /** Exception thrown by heur_gcd() to signal failure. */
1232 class gcdheu_failed {};
1234 /** Compute GCD of multivariate polynomials using the heuristic GCD algorithm.
1235 * get_symbol_stats() must have been called previously with the input
1236 * polynomials and an iterator to the first element of the sym_desc vector
1237 * passed in. This function is used internally by gcd().
1239 * @param a first multivariate polynomial (expanded)
1240 * @param b second multivariate polynomial (expanded)
1241 * @param ca cofactor of polynomial a (returned), NULL to suppress
1242 * calculation of cofactor
1243 * @param cb cofactor of polynomial b (returned), NULL to suppress
1244 * calculation of cofactor
1245 * @param var iterator to first element of vector of sym_desc structs
1246 * @return the GCD as a new expression
1248 * @exception gcdheu_failed() */
1249 static ex heur_gcd(const ex &a, const ex &b, ex *ca, ex *cb, sym_desc_vec::const_iterator var)
1251 //clog << "heur_gcd(" << a << "," << b << ")\n";
1256 // GCD of two numeric values -> CLN
1257 if (is_ex_exactly_of_type(a, numeric) && is_ex_exactly_of_type(b, numeric)) {
1258 numeric g = gcd(ex_to_numeric(a), ex_to_numeric(b));
1263 *ca = ex_to_numeric(a).mul(rg);
1265 *cb = ex_to_numeric(b).mul(rg);
1269 // The first symbol is our main variable
1270 const symbol *x = var->sym;
1272 // Remove integer content
1273 numeric gc = gcd(a.integer_content(), b.integer_content());
1274 numeric rgc = gc.inverse();
1277 int maxdeg = max(p.degree(*x), q.degree(*x));
1279 // Find evaluation point
1280 numeric mp = p.max_coefficient(), mq = q.max_coefficient();
1283 xi = mq * _num2() + _num2();
1285 xi = mp * _num2() + _num2();
1288 for (int t=0; t<6; t++) {
1289 if (xi.int_length() * maxdeg > 100000) {
1290 //clog << "giving up heur_gcd, xi.int_length = " << xi.int_length() << ", maxdeg = " << maxdeg << endl;
1291 throw gcdheu_failed();
1294 // Apply evaluation homomorphism and calculate GCD
1295 ex gamma = heur_gcd(p.subs(*x == xi), q.subs(*x == xi), NULL, NULL, var+1).expand();
1296 if (!is_ex_exactly_of_type(gamma, fail)) {
1298 // Reconstruct polynomial from GCD of mapped polynomials
1300 numeric rxi = xi.inverse();
1301 for (int i=0; !gamma.is_zero(); i++) {
1302 ex gi = gamma.smod(xi);
1303 g += gi * power(*x, i);
1304 gamma = (gamma - gi) * rxi;
1306 // Remove integer content
1307 g /= g.integer_content();
1309 // If the calculated polynomial divides both a and b, this is the GCD
1311 if (divide_in_z(p, g, ca ? *ca : dummy, var) && divide_in_z(q, g, cb ? *cb : dummy, var)) {
1313 ex lc = g.lcoeff(*x);
1314 if (is_ex_exactly_of_type(lc, numeric) && ex_to_numeric(lc).is_negative())
1321 // Next evaluation point
1322 xi = iquo(xi * isqrt(isqrt(xi)) * numeric(73794), numeric(27011));
1324 return *new ex(fail());
1328 /** Compute GCD (Greatest Common Divisor) of multivariate polynomials a(X)
1331 * @param a first multivariate polynomial
1332 * @param b second multivariate polynomial
1333 * @param check_args check whether a and b are polynomials with rational
1334 * coefficients (defaults to "true")
1335 * @return the GCD as a new expression */
1336 ex gcd(const ex &a, const ex &b, ex *ca, ex *cb, bool check_args)
1338 //clog << "gcd(" << a << "," << b << ")\n";
1343 // GCD of numerics -> CLN
1344 if (is_ex_exactly_of_type(a, numeric) && is_ex_exactly_of_type(b, numeric)) {
1345 numeric g = gcd(ex_to_numeric(a), ex_to_numeric(b));
1347 *ca = ex_to_numeric(a) / g;
1349 *cb = ex_to_numeric(b) / g;
1354 if (check_args && !a.info(info_flags::rational_polynomial) || !b.info(info_flags::rational_polynomial)) {
1355 throw(std::invalid_argument("gcd: arguments must be polynomials over the rationals"));
1358 // Partially factored cases (to avoid expanding large expressions)
1359 if (is_ex_exactly_of_type(a, mul)) {
1360 if (is_ex_exactly_of_type(b, mul) && b.nops() > a.nops())
1366 for (unsigned i=0; i<a.nops(); i++) {
1367 ex part_ca, part_cb;
1368 g *= gcd(a.op(i), part_b, &part_ca, &part_cb, check_args);
1377 } else if (is_ex_exactly_of_type(b, mul)) {
1378 if (is_ex_exactly_of_type(a, mul) && a.nops() > b.nops())
1384 for (unsigned i=0; i<b.nops(); i++) {
1385 ex part_ca, part_cb;
1386 g *= gcd(part_a, b.op(i), &part_ca, &part_cb, check_args);
1398 // Input polynomials of the form poly^n are sometimes also trivial
1399 if (is_ex_exactly_of_type(a, power)) {
1401 if (is_ex_exactly_of_type(b, power)) {
1402 if (p.is_equal(b.op(0))) {
1403 // a = p^n, b = p^m, gcd = p^min(n, m)
1404 ex exp_a = a.op(1), exp_b = b.op(1);
1405 if (exp_a < exp_b) {
1409 *cb = power(p, exp_b - exp_a);
1410 return power(p, exp_a);
1413 *ca = power(p, exp_a - exp_b);
1416 return power(p, exp_b);
1420 if (p.is_equal(b)) {
1421 // a = p^n, b = p, gcd = p
1423 *ca = power(p, a.op(1) - 1);
1429 } else if (is_ex_exactly_of_type(b, power)) {
1431 if (p.is_equal(a)) {
1432 // a = p, b = p^n, gcd = p
1436 *cb = power(p, b.op(1) - 1);
1442 // Some trivial cases
1443 ex aex = a.expand(), bex = b.expand();
1444 if (aex.is_zero()) {
1451 if (bex.is_zero()) {
1458 if (aex.is_equal(_ex1()) || bex.is_equal(_ex1())) {
1466 if (a.is_equal(b)) {
1475 // Gather symbol statistics
1476 sym_desc_vec sym_stats;
1477 get_symbol_stats(a, b, sym_stats);
1479 // The symbol with least degree is our main variable
1480 sym_desc_vec::const_iterator var = sym_stats.begin();
1481 const symbol *x = var->sym;
1483 // Cancel trivial common factor
1484 int ldeg_a = var->ldeg_a;
1485 int ldeg_b = var->ldeg_b;
1486 int min_ldeg = min(ldeg_a, ldeg_b);
1488 ex common = power(*x, min_ldeg);
1489 //clog << "trivial common factor " << common << endl;
1490 return gcd((aex / common).expand(), (bex / common).expand(), ca, cb, false) * common;
1493 // Try to eliminate variables
1494 if (var->deg_a == 0) {
1495 //clog << "eliminating variable " << *x << " from b" << endl;
1496 ex c = bex.content(*x);
1497 ex g = gcd(aex, c, ca, cb, false);
1499 *cb *= bex.unit(*x) * bex.primpart(*x, c);
1501 } else if (var->deg_b == 0) {
1502 //clog << "eliminating variable " << *x << " from a" << endl;
1503 ex c = aex.content(*x);
1504 ex g = gcd(c, bex, ca, cb, false);
1506 *ca *= aex.unit(*x) * aex.primpart(*x, c);
1512 // Try heuristic algorithm first, fall back to PRS if that failed
1514 g = heur_gcd(aex, bex, ca, cb, var);
1515 } catch (gcdheu_failed) {
1516 g = *new ex(fail());
1518 if (is_ex_exactly_of_type(g, fail)) {
1519 //clog << "heuristics failed" << endl;
1524 // g = heur_gcd(aex, bex, ca, cb, var);
1525 // g = eu_gcd(aex, bex, x);
1526 // g = euprem_gcd(aex, bex, x);
1527 // g = peu_gcd(aex, bex, x);
1528 // g = red_gcd(aex, bex, x);
1529 g = sr_gcd(aex, bex, x);
1530 if (g.is_equal(_ex1())) {
1531 // Keep cofactors factored if possible
1538 divide(aex, g, *ca, false);
1540 divide(bex, g, *cb, false);
1544 if (g.is_equal(_ex1())) {
1545 // Keep cofactors factored if possible
1557 /** Compute LCM (Least Common Multiple) of multivariate polynomials in Z[X].
1559 * @param a first multivariate polynomial
1560 * @param b second multivariate polynomial
1561 * @param check_args check whether a and b are polynomials with rational
1562 * coefficients (defaults to "true")
1563 * @return the LCM as a new expression */
1564 ex lcm(const ex &a, const ex &b, bool check_args)
1566 if (is_ex_exactly_of_type(a, numeric) && is_ex_exactly_of_type(b, numeric))
1567 return lcm(ex_to_numeric(a), ex_to_numeric(b));
1568 if (check_args && !a.info(info_flags::rational_polynomial) || !b.info(info_flags::rational_polynomial))
1569 throw(std::invalid_argument("lcm: arguments must be polynomials over the rationals"));
1572 ex g = gcd(a, b, &ca, &cb, false);
1578 * Square-free factorization
1581 // Univariate GCD of polynomials in Q[x] (used internally by sqrfree()).
1582 // a and b can be multivariate polynomials but they are treated as univariate polynomials in x.
1583 static ex univariate_gcd(const ex &a, const ex &b, const symbol &x)
1589 if (a.is_equal(_ex1()) || b.is_equal(_ex1()))
1591 if (is_ex_of_type(a, numeric) && is_ex_of_type(b, numeric))
1592 return gcd(ex_to_numeric(a), ex_to_numeric(b));
1593 if (!a.info(info_flags::rational_polynomial) || !b.info(info_flags::rational_polynomial))
1594 throw(std::invalid_argument("univariate_gcd: arguments must be polynomials over the rationals"));
1596 // Euclidean algorithm
1598 if (a.degree(x) >= b.degree(x)) {
1606 r = rem(c, d, x, false);
1612 return d / d.lcoeff(x);
1616 /** Compute square-free factorization of multivariate polynomial a(x) using
1619 * @param a multivariate polynomial
1620 * @param x variable to factor in
1621 * @return factored polynomial */
1622 ex sqrfree(const ex &a, const symbol &x)
1627 ex c = univariate_gcd(a, b, x);
1629 if (c.is_equal(_ex1())) {
1633 ex y = quo(b, c, x);
1634 ex z = y - w.diff(x);
1635 while (!z.is_zero()) {
1636 ex g = univariate_gcd(w, z, x);
1644 return res * power(w, i);
1649 * Normal form of rational functions
1653 * Note: The internal normal() functions (= basic::normal() and overloaded
1654 * functions) all return lists of the form {numerator, denominator}. This
1655 * is to get around mul::eval()'s automatic expansion of numeric coefficients.
1656 * E.g. (a+b)/3 is automatically converted to a/3+b/3 but we want to keep
1657 * the information that (a+b) is the numerator and 3 is the denominator.
1660 /** Create a symbol for replacing the expression "e" (or return a previously
1661 * assigned symbol). The symbol is appended to sym_lst and returned, the
1662 * expression is appended to repl_lst.
1663 * @see ex::normal */
1664 static ex replace_with_symbol(const ex &e, lst &sym_lst, lst &repl_lst)
1666 // Expression already in repl_lst? Then return the assigned symbol
1667 for (unsigned i=0; i<repl_lst.nops(); i++)
1668 if (repl_lst.op(i).is_equal(e))
1669 return sym_lst.op(i);
1671 // Otherwise create new symbol and add to list, taking care that the
1672 // replacement expression doesn't contain symbols from the sym_lst
1673 // because subs() is not recursive
1676 ex e_replaced = e.subs(sym_lst, repl_lst);
1678 repl_lst.append(e_replaced);
1682 /** Create a symbol for replacing the expression "e" (or return a previously
1683 * assigned symbol). An expression of the form "symbol == expression" is added
1684 * to repl_lst and the symbol is returned.
1685 * @see ex::to_rational */
1686 static ex replace_with_symbol(const ex &e, lst &repl_lst)
1688 // Expression already in repl_lst? Then return the assigned symbol
1689 for (unsigned i=0; i<repl_lst.nops(); i++)
1690 if (repl_lst.op(i).op(1).is_equal(e))
1691 return repl_lst.op(i).op(0);
1693 // Otherwise create new symbol and add to list, taking care that the
1694 // replacement expression doesn't contain symbols from the sym_lst
1695 // because subs() is not recursive
1698 ex e_replaced = e.subs(repl_lst);
1699 repl_lst.append(es == e_replaced);
1703 /** Default implementation of ex::normal(). It replaces the object with a
1705 * @see ex::normal */
1706 ex basic::normal(lst &sym_lst, lst &repl_lst, int level) const
1708 return (new lst(replace_with_symbol(*this, sym_lst, repl_lst), _ex1()))->setflag(status_flags::dynallocated);
1712 /** Implementation of ex::normal() for symbols. This returns the unmodified symbol.
1713 * @see ex::normal */
1714 ex symbol::normal(lst &sym_lst, lst &repl_lst, int level) const
1716 return (new lst(*this, _ex1()))->setflag(status_flags::dynallocated);
1720 /** Implementation of ex::normal() for a numeric. It splits complex numbers
1721 * into re+I*im and replaces I and non-rational real numbers with a temporary
1723 * @see ex::normal */
1724 ex numeric::normal(lst &sym_lst, lst &repl_lst, int level) const
1726 numeric num = numer();
1729 if (num.is_real()) {
1730 if (!num.is_integer())
1731 numex = replace_with_symbol(numex, sym_lst, repl_lst);
1733 numeric re = num.real(), im = num.imag();
1734 ex re_ex = re.is_rational() ? re : replace_with_symbol(re, sym_lst, repl_lst);
1735 ex im_ex = im.is_rational() ? im : replace_with_symbol(im, sym_lst, repl_lst);
1736 numex = re_ex + im_ex * replace_with_symbol(I, sym_lst, repl_lst);
1739 // Denominator is always a real integer (see numeric::denom())
1740 return (new lst(numex, denom()))->setflag(status_flags::dynallocated);
1744 /** Fraction cancellation.
1745 * @param n numerator
1746 * @param d denominator
1747 * @return cancelled fraction {n, d} as a list */
1748 static ex frac_cancel(const ex &n, const ex &d)
1752 numeric pre_factor = _num1();
1754 //clog << "frac_cancel num = " << num << ", den = " << den << endl;
1756 // Handle special cases where numerator or denominator is 0
1758 return (new lst(_ex0(), _ex1()))->setflag(status_flags::dynallocated);
1759 if (den.expand().is_zero())
1760 throw(std::overflow_error("frac_cancel: division by zero in frac_cancel"));
1762 // Bring numerator and denominator to Z[X] by multiplying with
1763 // LCM of all coefficients' denominators
1764 numeric num_lcm = lcm_of_coefficients_denominators(num);
1765 numeric den_lcm = lcm_of_coefficients_denominators(den);
1766 num = multiply_lcm(num, num_lcm);
1767 den = multiply_lcm(den, den_lcm);
1768 pre_factor = den_lcm / num_lcm;
1770 // Cancel GCD from numerator and denominator
1772 if (gcd(num, den, &cnum, &cden, false) != _ex1()) {
1777 // Make denominator unit normal (i.e. coefficient of first symbol
1778 // as defined by get_first_symbol() is made positive)
1780 if (get_first_symbol(den, x)) {
1781 GINAC_ASSERT(is_ex_exactly_of_type(den.unit(*x),numeric));
1782 if (ex_to_numeric(den.unit(*x)).is_negative()) {
1788 // Return result as list
1789 //clog << " returns num = " << num << ", den = " << den << ", pre_factor = " << pre_factor << endl;
1790 return (new lst(num * pre_factor.numer(), den * pre_factor.denom()))->setflag(status_flags::dynallocated);
1794 /** Implementation of ex::normal() for a sum. It expands terms and performs
1795 * fractional addition.
1796 * @see ex::normal */
1797 ex add::normal(lst &sym_lst, lst &repl_lst, int level) const
1799 // Normalize and expand children, chop into summands
1801 o.reserve(seq.size()+1);
1802 epvector::const_iterator it = seq.begin(), itend = seq.end();
1803 while (it != itend) {
1805 // Normalize and expand child
1806 ex n = recombine_pair_to_ex(*it).bp->normal(sym_lst, repl_lst, level-1).expand();
1808 // If numerator is a sum, chop into summands
1809 if (is_ex_exactly_of_type(n.op(0), add)) {
1810 epvector::const_iterator bit = ex_to_add(n.op(0)).seq.begin(), bitend = ex_to_add(n.op(0)).seq.end();
1811 while (bit != bitend) {
1812 o.push_back((new lst(recombine_pair_to_ex(*bit), n.op(1)))->setflag(status_flags::dynallocated));
1816 // The overall_coeff is already normalized (== rational), we just
1817 // split it into numerator and denominator
1818 GINAC_ASSERT(ex_to_numeric(ex_to_add(n.op(0)).overall_coeff).is_rational());
1819 numeric overall = ex_to_numeric(ex_to_add(n.op(0)).overall_coeff);
1820 o.push_back((new lst(overall.numer(), overall.denom() * n.op(1)))->setflag(status_flags::dynallocated));
1825 o.push_back(overall_coeff.bp->normal(sym_lst, repl_lst, level-1));
1827 // o is now a vector of {numerator, denominator} lists
1829 // Determine common denominator
1831 exvector::const_iterator ait = o.begin(), aitend = o.end();
1832 //clog << "add::normal uses the following summands:\n";
1833 while (ait != aitend) {
1834 //clog << " num = " << ait->op(0) << ", den = " << ait->op(1) << endl;
1835 den = lcm(ait->op(1), den, false);
1838 //clog << " common denominator = " << den << endl;
1841 if (den.is_equal(_ex1())) {
1843 // Common denominator is 1, simply add all numerators
1845 for (ait=o.begin(); ait!=aitend; ait++) {
1846 num_seq.push_back(ait->op(0));
1848 return (new lst((new add(num_seq))->setflag(status_flags::dynallocated), den))->setflag(status_flags::dynallocated);
1852 // Perform fractional addition
1854 for (ait=o.begin(); ait!=aitend; ait++) {
1856 if (!divide(den, ait->op(1), q, false)) {
1857 // should not happen
1858 throw(std::runtime_error("invalid expression in add::normal, division failed"));
1860 num_seq.push_back((ait->op(0) * q).expand());
1862 ex num = (new add(num_seq))->setflag(status_flags::dynallocated);
1864 // Cancel common factors from num/den
1865 return frac_cancel(num, den);
1870 /** Implementation of ex::normal() for a product. It cancels common factors
1872 * @see ex::normal() */
1873 ex mul::normal(lst &sym_lst, lst &repl_lst, int level) const
1875 // Normalize children, separate into numerator and denominator
1879 epvector::const_iterator it = seq.begin(), itend = seq.end();
1880 while (it != itend) {
1881 n = recombine_pair_to_ex(*it).bp->normal(sym_lst, repl_lst, level-1);
1886 n = overall_coeff.bp->normal(sym_lst, repl_lst, level-1);
1890 // Perform fraction cancellation
1891 return frac_cancel(num, den);
1895 /** Implementation of ex::normal() for powers. It normalizes the basis,
1896 * distributes integer exponents to numerator and denominator, and replaces
1897 * non-integer powers by temporary symbols.
1898 * @see ex::normal */
1899 ex power::normal(lst &sym_lst, lst &repl_lst, int level) const
1902 ex n = basis.bp->normal(sym_lst, repl_lst, level-1);
1904 if (exponent.info(info_flags::integer)) {
1906 if (exponent.info(info_flags::positive)) {
1908 // (a/b)^n -> {a^n, b^n}
1909 return (new lst(power(n.op(0), exponent), power(n.op(1), exponent)))->setflag(status_flags::dynallocated);
1911 } else if (exponent.info(info_flags::negative)) {
1913 // (a/b)^-n -> {b^n, a^n}
1914 return (new lst(power(n.op(1), -exponent), power(n.op(0), -exponent)))->setflag(status_flags::dynallocated);
1919 if (exponent.info(info_flags::positive)) {
1921 // (a/b)^x -> {sym((a/b)^x), 1}
1922 return (new lst(replace_with_symbol(power(n.op(0) / n.op(1), exponent), sym_lst, repl_lst), _ex1()))->setflag(status_flags::dynallocated);
1924 } else if (exponent.info(info_flags::negative)) {
1926 if (n.op(1).is_equal(_ex1())) {
1928 // a^-x -> {1, sym(a^x)}
1929 return (new lst(_ex1(), replace_with_symbol(power(n.op(0), -exponent), sym_lst, repl_lst)))->setflag(status_flags::dynallocated);
1933 // (a/b)^-x -> {sym((b/a)^x), 1}
1934 return (new lst(replace_with_symbol(power(n.op(1) / n.op(0), -exponent), sym_lst, repl_lst), _ex1()))->setflag(status_flags::dynallocated);
1937 } else { // exponent not numeric
1939 // (a/b)^x -> {sym((a/b)^x, 1}
1940 return (new lst(replace_with_symbol(power(n.op(0) / n.op(1), exponent), sym_lst, repl_lst), _ex1()))->setflag(status_flags::dynallocated);
1946 /** Implementation of ex::normal() for pseries. It normalizes each coefficient and
1947 * replaces the series by a temporary symbol.
1948 * @see ex::normal */
1949 ex pseries::normal(lst &sym_lst, lst &repl_lst, int level) const
1952 new_seq.reserve(seq.size());
1954 epvector::const_iterator it = seq.begin(), itend = seq.end();
1955 while (it != itend) {
1956 new_seq.push_back(expair(it->rest.normal(), it->coeff));
1959 ex n = pseries(relational(var,point), new_seq);
1960 return (new lst(replace_with_symbol(n, sym_lst, repl_lst), _ex1()))->setflag(status_flags::dynallocated);
1964 /** Implementation of ex::normal() for relationals. It normalizes both sides.
1965 * @see ex::normal */
1966 ex relational::normal(lst &sym_lst, lst &repl_lst, int level) const
1968 return (new lst(relational(lh.normal(), rh.normal(), o), _ex1()))->setflag(status_flags::dynallocated);
1972 /** Normalization of rational functions.
1973 * This function converts an expression to its normal form
1974 * "numerator/denominator", where numerator and denominator are (relatively
1975 * prime) polynomials. Any subexpressions which are not rational functions
1976 * (like non-rational numbers, non-integer powers or functions like sin(),
1977 * cos() etc.) are replaced by temporary symbols which are re-substituted by
1978 * the (normalized) subexpressions before normal() returns (this way, any
1979 * expression can be treated as a rational function). normal() is applied
1980 * recursively to arguments of functions etc.
1982 * @param level maximum depth of recursion
1983 * @return normalized expression */
1984 ex ex::normal(int level) const
1986 lst sym_lst, repl_lst;
1988 ex e = bp->normal(sym_lst, repl_lst, level);
1989 GINAC_ASSERT(is_ex_of_type(e, lst));
1991 // Re-insert replaced symbols
1992 if (sym_lst.nops() > 0)
1993 e = e.subs(sym_lst, repl_lst);
1995 // Convert {numerator, denominator} form back to fraction
1996 return e.op(0) / e.op(1);
1999 /** Numerator of an expression. If the expression is not of the normal form
2000 * "numerator/denominator", it is first converted to this form and then the
2001 * numerator is returned.
2004 * @return numerator */
2005 ex ex::numer(void) const
2007 lst sym_lst, repl_lst;
2009 ex e = bp->normal(sym_lst, repl_lst, 0);
2010 GINAC_ASSERT(is_ex_of_type(e, lst));
2012 // Re-insert replaced symbols
2013 if (sym_lst.nops() > 0)
2014 return e.op(0).subs(sym_lst, repl_lst);
2019 /** Denominator of an expression. If the expression is not of the normal form
2020 * "numerator/denominator", it is first converted to this form and then the
2021 * denominator is returned.
2024 * @return denominator */
2025 ex ex::denom(void) const
2027 lst sym_lst, repl_lst;
2029 ex e = bp->normal(sym_lst, repl_lst, 0);
2030 GINAC_ASSERT(is_ex_of_type(e, lst));
2032 // Re-insert replaced symbols
2033 if (sym_lst.nops() > 0)
2034 return e.op(1).subs(sym_lst, repl_lst);
2040 /** Default implementation of ex::to_rational(). It replaces the object with a
2042 * @see ex::to_rational */
2043 ex basic::to_rational(lst &repl_lst) const
2045 return replace_with_symbol(*this, repl_lst);
2049 /** Implementation of ex::to_rational() for symbols. This returns the unmodified symbol.
2050 * @see ex::to_rational */
2051 ex symbol::to_rational(lst &repl_lst) const
2057 /** Implementation of ex::to_rational() for a numeric. It splits complex numbers
2058 * into re+I*im and replaces I and non-rational real numbers with a temporary
2060 * @see ex::to_rational */
2061 ex numeric::to_rational(lst &repl_lst) const
2065 return replace_with_symbol(*this, repl_lst);
2067 numeric re = real();
2068 numeric im = imag();
2069 ex re_ex = re.is_rational() ? re : replace_with_symbol(re, repl_lst);
2070 ex im_ex = im.is_rational() ? im : replace_with_symbol(im, repl_lst);
2071 return re_ex + im_ex * replace_with_symbol(I, repl_lst);
2077 /** Implementation of ex::to_rational() for powers. It replaces non-integer
2078 * powers by temporary symbols.
2079 * @see ex::to_rational */
2080 ex power::to_rational(lst &repl_lst) const
2082 if (exponent.info(info_flags::integer))
2083 return power(basis.to_rational(repl_lst), exponent);
2085 return replace_with_symbol(*this, repl_lst);
2089 /** Implementation of ex::to_rational() for expairseqs.
2090 * @see ex::to_rational */
2091 ex expairseq::to_rational(lst &repl_lst) const
2094 s.reserve(seq.size());
2095 for (epvector::const_iterator it=seq.begin(); it!=seq.end(); ++it) {
2096 s.push_back(split_ex_to_pair(recombine_pair_to_ex(*it).to_rational(repl_lst)));
2097 // s.push_back(combine_ex_with_coeff_to_pair((*it).rest.to_rational(repl_lst),
2099 ex oc = overall_coeff.to_rational(repl_lst);
2100 if (oc.info(info_flags::numeric))
2101 return thisexpairseq(s, overall_coeff);
2102 else s.push_back(combine_ex_with_coeff_to_pair(oc,_ex1()));
2103 return thisexpairseq(s, default_overall_coeff());
2107 /** Rationalization of non-rational functions.
2108 * This function converts a general expression to a rational polynomial
2109 * by replacing all non-rational subexpressions (like non-rational numbers,
2110 * non-integer powers or functions like sin(), cos() etc.) to temporary
2111 * symbols. This makes it possible to use functions like gcd() and divide()
2112 * on non-rational functions by applying to_rational() on the arguments,
2113 * calling the desired function and re-substituting the temporary symbols
2114 * in the result. To make the last step possible, all temporary symbols and
2115 * their associated expressions are collected in the list specified by the
2116 * repl_lst parameter in the form {symbol == expression}, ready to be passed
2117 * as an argument to ex::subs().
2119 * @param repl_lst collects a list of all temporary symbols and their replacements
2120 * @return rationalized expression */
2121 ex ex::to_rational(lst &repl_lst) const
2123 return bp->to_rational(repl_lst);
2127 #ifndef NO_NAMESPACE_GINAC
2128 } // namespace GiNaC
2129 #endif // ndef NO_NAMESPACE_GINAC