ginac/mul.cpp

   1 /** @file mul.cpp
   2  *
   3  *  Implementation of GiNaC's products of expressions. */
   4
   5 /*
   6  *  GiNaC Copyright (C) 1999-2015 Johannes Gutenberg University Mainz, Germany
   7  *
   8  *  This program is free software; you can redistribute it and/or modify
   9  *  it under the terms of the GNU General Public License as published by
  10  *  the Free Software Foundation; either version 2 of the License, or
  11  *  (at your option) any later version.
  12  *
  13  *  This program is distributed in the hope that it will be useful,
  14  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  *  GNU General Public License for more details.
  17  *
  18  *  You should have received a copy of the GNU General Public License
  19  *  along with this program; if not, write to the Free Software
  20  *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  21  */
  22
  23 #include "mul.h"
  24 #include "add.h"
  25 #include "power.h"
  26 #include "operators.h"
  27 #include "matrix.h"
  28 #include "indexed.h"
  29 #include "lst.h"
  30 #include "archive.h"
  31 #include "utils.h"
  32 #include "symbol.h"
  33 #include "compiler.h"
  34
  35 #include <iostream>
  36 #include <limits>
  37 #include <stdexcept>
  38 #include <vector>
  39
  40 namespace GiNaC {
  41
  42 GINAC_IMPLEMENT_REGISTERED_CLASS_OPT(mul, expairseq,
  43   print_func<print_context>(&mul::do_print).
  44   print_func<print_latex>(&mul::do_print_latex).
  45   print_func<print_csrc>(&mul::do_print_csrc).
  46   print_func<print_tree>(&mul::do_print_tree).
  47   print_func<print_python_repr>(&mul::do_print_python_repr))
  48
  49
  50 //////////
  51 // default constructor
  52 //////////
  53
  54 mul::mul()
  55 {
  56 }
  57
  58 //////////
  59 // other constructors
  60 //////////
  61
  62 // public
  63
  64 mul::mul(const ex & lh, const ex & rh)
  65 {
  66         overall_coeff = _ex1;
  67         construct_from_2_ex(lh,rh);
  68         GINAC_ASSERT(is_canonical());
  69 }
  70
  71 mul::mul(const exvector & v)
  72 {
  73         overall_coeff = _ex1;
  74         construct_from_exvector(v);
  75         GINAC_ASSERT(is_canonical());
  76 }
  77
  78 mul::mul(const epvector & v)
  79 {
  80         overall_coeff = _ex1;
  81         construct_from_epvector(v);
  82         GINAC_ASSERT(is_canonical());
  83 }
  84
  85 mul::mul(const epvector & v, const ex & oc, bool do_index_renaming)
  86 {
  87         overall_coeff = oc;
  88         construct_from_epvector(v, do_index_renaming);
  89         GINAC_ASSERT(is_canonical());
  90 }
  91
  92 mul::mul(epvector && vp, const ex & oc, bool do_index_renaming)
  93 {
  94         overall_coeff = oc;
  95         construct_from_epvector(std::move(vp), do_index_renaming);
  96         GINAC_ASSERT(is_canonical());
  97 }
  98
  99 mul::mul(const ex & lh, const ex & mh, const ex & rh)
 100 {
 101         exvector factors;
 102         factors.reserve(3);
 103         factors.push_back(lh);
 104         factors.push_back(mh);
 105         factors.push_back(rh);
 106         overall_coeff = _ex1;
 107         construct_from_exvector(factors);
 108         GINAC_ASSERT(is_canonical());
 109 }
 110
 111 //////////
 112 // archiving
 113 //////////
 114
 115 //////////
 116 // functions overriding virtual functions from base classes
 117 //////////
 118
 119 void mul::print_overall_coeff(const print_context & c, const char *mul_sym) const
 120 {
 121         const numeric &coeff = ex_to<numeric>(overall_coeff);
 122         if (coeff.csgn() == -1)
 123                 c.s << '-';
 124         if (!coeff.is_equal(*_num1_p) &&
 125                 !coeff.is_equal(*_num_1_p)) {
 126                 if (coeff.is_rational()) {
 127                         if (coeff.is_negative())
 128                                 (-coeff).print(c);
 129                         else
 130                                 coeff.print(c);
 131                 } else {
 132                         if (coeff.csgn() == -1)
 133                                 (-coeff).print(c, precedence());
 134                         else
 135                                 coeff.print(c, precedence());
 136                 }
 137                 c.s << mul_sym;
 138         }
 139 }
 140
 141 void mul::do_print(const print_context & c, unsigned level) const
 142 {
 143         if (precedence() <= level)
 144                 c.s << '(';
 145
 146         print_overall_coeff(c, "*");
 147
 148         bool first = true;
 149         for (auto & it : seq) {
 150                 if (!first)
 151                         c.s << '*';
 152                 else
 153                         first = false;
 154                 recombine_pair_to_ex(it).print(c, precedence());
 155         }
 156
 157         if (precedence() <= level)
 158                 c.s << ')';
 159 }
 160
 161 void mul::do_print_latex(const print_latex & c, unsigned level) const
 162 {
 163         if (precedence() <= level)
 164                 c.s << "{(";
 165
 166         print_overall_coeff(c, " ");
 167
 168         // Separate factors into those with negative numeric exponent
 169         // and all others
 170         exvector neg_powers, others;
 171         for (auto & it : seq) {
 172                 GINAC_ASSERT(is_exactly_a<numeric>(it.coeff));
 173                 if (ex_to<numeric>(it.coeff).is_negative())
 174                         neg_powers.push_back(recombine_pair_to_ex(expair(it.rest, -it.coeff)));
 175                 else
 176                         others.push_back(recombine_pair_to_ex(it));
 177         }
 178
 179         if (!neg_powers.empty()) {
 180
 181                 // Factors with negative exponent are printed as a fraction
 182                 c.s << "\\frac{";
 183                 mul(others).eval().print(c);
 184                 c.s << "}{";
 185                 mul(neg_powers).eval().print(c);
 186                 c.s << "}";
 187
 188         } else {
 189
 190                 // All other factors are printed in the ordinary way
 191                 for (auto & vit : others) {
 192                         c.s << ' ';
 193                         vit.print(c, precedence());
 194                 }
 195         }
 196
 197         if (precedence() <= level)
 198                 c.s << ")}";
 199 }
 200
 201 void mul::do_print_csrc(const print_csrc & c, unsigned level) const
 202 {
 203         if (precedence() <= level)
 204                 c.s << "(";
 205
 206         if (!overall_coeff.is_equal(_ex1)) {
 207                 if (overall_coeff.is_equal(_ex_1))
 208                         c.s << "-";
 209                 else {
 210                         overall_coeff.print(c, precedence());
 211                         c.s << "*";
 212                 }
 213         }
 214
 215         // Print arguments, separated by "*" or "/"
 216         auto it = seq.begin(), itend = seq.end();
 217         while (it != itend) {
 218
 219                 // If the first argument is a negative integer power, it gets printed as "1.0/<expr>"
 220                 bool needclosingparenthesis = false;
 221                 if (it == seq.begin() && it->coeff.info(info_flags::negint)) {
 222                         if (is_a<print_csrc_cl_N>(c)) {
 223                                 c.s << "recip(";
 224                                 needclosingparenthesis = true;
 225                         } else
 226                                 c.s << "1.0/";
 227                 }
 228
 229                 // If the exponent is 1 or -1, it is left out
 230                 if (it->coeff.is_equal(_ex1) || it->coeff.is_equal(_ex_1))
 231                         it->rest.print(c, precedence());
 232                 else if (it->coeff.info(info_flags::negint))
 233                         ex(power(it->rest, -ex_to<numeric>(it->coeff))).print(c, level);
 234                 else
 235                         ex(power(it->rest, ex_to<numeric>(it->coeff))).print(c, level);
 236
 237                 if (needclosingparenthesis)
 238                         c.s << ")";
 239
 240                 // Separator is "/" for negative integer powers, "*" otherwise
 241                 ++it;
 242                 if (it != itend) {
 243                         if (it->coeff.info(info_flags::negint))
 244                                 c.s << "/";
 245                         else
 246                                 c.s << "*";
 247                 }
 248         }
 249
 250         if (precedence() <= level)
 251                 c.s << ")";
 252 }
 253
 254 void mul::do_print_python_repr(const print_python_repr & c, unsigned level) const
 255 {
 256         c.s << class_name() << '(';
 257         op(0).print(c);
 258         for (size_t i=1; i<nops(); ++i) {
 259                 c.s << ',';
 260                 op(i).print(c);
 261         }
 262         c.s << ')';
 263 }
 264
 265 bool mul::info(unsigned inf) const
 266 {
 267         switch (inf) {
 268                 case info_flags::polynomial:
 269                 case info_flags::integer_polynomial:
 270                 case info_flags::cinteger_polynomial:
 271                 case info_flags::rational_polynomial:
 272                 case info_flags::real:
 273                 case info_flags::rational:
 274                 case info_flags::integer:
 275                 case info_flags::crational:
 276                 case info_flags::cinteger:
 277                 case info_flags::even:
 278                 case info_flags::crational_polynomial:
 279                 case info_flags::rational_function: {
 280                         for (auto & it : seq) {
 281                                 if (!recombine_pair_to_ex(it).info(inf))
 282                                         return false;
 283                         }
 284                         if (overall_coeff.is_equal(*_num1_p) && inf == info_flags::even)
 285                                 return true;
 286                         return overall_coeff.info(inf);
 287                 }
 288                 case info_flags::algebraic: {
 289                         for (auto & it : seq) {
 290                                 if (recombine_pair_to_ex(it).info(inf))
 291                                         return true;
 292                         }
 293                         return false;
 294                 }
 295                 case info_flags::positive:
 296                 case info_flags::negative: {
 297                         if ((inf==info_flags::positive) && (flags & status_flags::is_positive))
 298                                 return true;
 299                         else if ((inf==info_flags::negative) && (flags & status_flags::is_negative))
 300                                 return true;
 301                         if (flags & status_flags::purely_indefinite)
 302                                 return false;
 303
 304                         bool pos = true;
 305                         for (auto & it : seq) {
 306                                 const ex& factor = recombine_pair_to_ex(it);
 307                                 if (factor.info(info_flags::positive))
 308                                         continue;
 309                                 else if (factor.info(info_flags::negative))
 310                                         pos = !pos;
 311                                 else
 312                                         return false;
 313                         }
 314                         if (overall_coeff.info(info_flags::negative))
 315                                 pos = !pos;
 316                         setflag(pos ? status_flags::is_positive : status_flags::is_negative);
 317                         return (inf == info_flags::positive? pos : !pos);
 318                 }
 319                 case info_flags::nonnegative: {
 320                         if  (flags & status_flags::is_positive)
 321                                 return true;
 322                         bool pos = true;
 323                         for (auto & it : seq) {
 324                                 const ex& factor = recombine_pair_to_ex(it);
 325                                 if (factor.info(info_flags::nonnegative) || factor.info(info_flags::positive))
 326                                         continue;
 327                                 else if (factor.info(info_flags::negative))
 328                                         pos = !pos;
 329                                 else
 330                                         return false;
 331                         }
 332                         return (overall_coeff.info(info_flags::negative)? !pos : pos);
 333                 }
 334                 case info_flags::posint:
 335                 case info_flags::negint: {
 336                         bool pos = true;
 337                         for (auto & it : seq) {
 338                                 const ex& factor = recombine_pair_to_ex(it);
 339                                 if (factor.info(info_flags::posint))
 340                                         continue;
 341                                 else if (factor.info(info_flags::negint))
 342                                         pos = !pos;
 343                                 else
 344                                         return false;
 345                         }
 346                         if (overall_coeff.info(info_flags::negint))
 347                                 pos = !pos;
 348                         else if (!overall_coeff.info(info_flags::posint))
 349                                 return false;
 350                         return (inf ==info_flags::posint? pos : !pos);
 351                 }
 352                 case info_flags::nonnegint: {
 353                         bool pos = true;
 354                         for (auto & it : seq) {
 355                                 const ex& factor = recombine_pair_to_ex(it);
 356                                 if (factor.info(info_flags::nonnegint) || factor.info(info_flags::posint))
 357                                         continue;
 358                                 else if (factor.info(info_flags::negint))
 359                                         pos = !pos;
 360                                 else
 361                                         return false;
 362                         }
 363                         if (overall_coeff.info(info_flags::negint))
 364                                 pos = !pos;
 365                         else if (!overall_coeff.info(info_flags::posint))
 366                                 return false;
 367                         return pos;
 368                 }
 369                 case info_flags::indefinite: {
 370                         if (flags & status_flags::purely_indefinite)
 371                                 return true;
 372                         if (flags & (status_flags::is_positive | status_flags::is_negative))
 373                                 return false;
 374                         for (auto & it : seq) {
 375                                 const ex& term = recombine_pair_to_ex(it);
 376                                 if (term.info(info_flags::positive) || term.info(info_flags::negative))
 377                                         return false;
 378                         }
 379                         setflag(status_flags::purely_indefinite);
 380                         return true;
 381                 }
 382         }
 383         return inherited::info(inf);
 384 }
 385
 386 bool mul::is_polynomial(const ex & var) const
 387 {
 388         for (auto & it : seq) {
 389                 if (!it.rest.is_polynomial(var) ||
 390                     (it.rest.has(var) && !it.coeff.info(info_flags::nonnegint))) {
 391                         return false;
 392                 }
 393         }
 394         return true;
 395 }
 396
 397 int mul::degree(const ex & s) const
 398 {
 399         // Sum up degrees of factors
 400         int deg_sum = 0;
 401         for (auto & it : seq) {
 402                 if (ex_to<numeric>(it.coeff).is_integer())
 403                         deg_sum += recombine_pair_to_ex(it).degree(s);
 404                 else {
 405                         if (it.rest.has(s))
 406                                 throw std::runtime_error("mul::degree() undefined degree because of non-integer exponent");
 407                 }
 408         }
 409         return deg_sum;
 410 }
 411
 412 int mul::ldegree(const ex & s) const
 413 {
 414         // Sum up degrees of factors
 415         int deg_sum = 0;
 416         for (auto & it : seq) {
 417                 if (ex_to<numeric>(it.coeff).is_integer())
 418                         deg_sum += recombine_pair_to_ex(it).ldegree(s);
 419                 else {
 420                         if (it.rest.has(s))
 421                                 throw std::runtime_error("mul::ldegree() undefined degree because of non-integer exponent");
 422                 }
 423         }
 424         return deg_sum;
 425 }
 426
 427 ex mul::coeff(const ex & s, int n) const
 428 {
 429         exvector coeffseq;
 430         coeffseq.reserve(seq.size()+1);
 431
 432         if (n==0) {
 433                 // product of individual coeffs
 434                 // if a non-zero power of s is found, the resulting product will be 0
 435                 for (auto & it : seq)
 436                         coeffseq.push_back(recombine_pair_to_ex(it).coeff(s,n));
 437                 coeffseq.push_back(overall_coeff);
 438                 return (new mul(coeffseq))->setflag(status_flags::dynallocated);
 439         }
 440
 441         bool coeff_found = false;
 442         for (auto & it : seq) {
 443                 ex t = recombine_pair_to_ex(it);
 444                 ex c = t.coeff(s, n);
 445                 if (!c.is_zero()) {
 446                         coeffseq.push_back(c);
 447                         coeff_found = 1;
 448                 } else {
 449                         coeffseq.push_back(t);
 450                 }
 451         }
 452         if (coeff_found) {
 453                 coeffseq.push_back(overall_coeff);
 454                 return (new mul(coeffseq))->setflag(status_flags::dynallocated);
 455         }
 456
 457         return _ex0;
 458 }
 459
 460 /** Perform automatic term rewriting rules in this class.  In the following
 461  *  x, x1, x2,... stand for a symbolic variables of type ex and c, c1, c2...
 462  *  stand for such expressions that contain a plain number.
 463  *  - *(...,x;0) -> 0
 464  *  - *(+(x1,x2,...);c) -> *(+(*(x1,c),*(x2,c),...))
 465  *  - *(x;1) -> x
 466  *  - *(;c) -> c
 467  *
 468  *  @param level cut-off in recursive evaluation */
 469 ex mul::eval(int level) const
 470 {
 471         epvector evaled = evalchildren(level);
 472         if (unlikely(!evaled.empty())) {
 473                 // do more evaluation later
 474                 return (new mul(std::move(evaled), overall_coeff))->
 475                         setflag(status_flags::dynallocated);
 476         }
 477
 478         if (flags & status_flags::evaluated) {
 479                 GINAC_ASSERT(seq.size()>0);
 480                 GINAC_ASSERT(seq.size()>1 || !overall_coeff.is_equal(_ex1));
 481                 return *this;
 482         }
 483
 484         size_t seq_size = seq.size();
 485         if (overall_coeff.is_zero()) {
 486                 // *(...,x;0) -> 0
 487                 return _ex0;
 488         } else if (seq_size==0) {
 489                 // *(;c) -> c
 490                 return overall_coeff;
 491         } else if (seq_size==1 && overall_coeff.is_equal(_ex1)) {
 492                 // *(x;1) -> x
 493                 return recombine_pair_to_ex(*(seq.begin()));
 494         } else if ((seq_size==1) &&
 495                    is_exactly_a<add>((*seq.begin()).rest) &&
 496                    ex_to<numeric>((*seq.begin()).coeff).is_equal(*_num1_p)) {
 497                 // *(+(x,y,...);c) -> +(*(x,c),*(y,c),...) (c numeric(), no powers of +())
 498                 const add & addref = ex_to<add>((*seq.begin()).rest);
 499                 epvector distrseq;
 500                 distrseq.reserve(addref.seq.size());
 501                 for (auto & it : addref.seq) {
 502                         distrseq.push_back(addref.combine_pair_with_coeff_to_pair(it, overall_coeff));
 503                 }
 504                 return (new add(std::move(distrseq),
 505                                 ex_to<numeric>(addref.overall_coeff).
 506                                 mul_dyn(ex_to<numeric>(overall_coeff)))
 507                        )->setflag(status_flags::dynallocated | status_flags::evaluated);
 508         } else if ((seq_size >= 2) && (! (flags & status_flags::expanded))) {
 509                 // Strip the content and the unit part from each term. Thus
 510                 // things like (-x+a)*(3*x-3*a) automagically turn into - 3*(x-a)^2
 511
 512                 auto i = seq.begin(), last = seq.end();
 513                 auto j = seq.begin();
 514                 epvector s;
 515                 numeric oc = *_num1_p;
 516                 bool something_changed = false;
 517                 while (i!=last) {
 518                         if (likely(! (is_a<add>(i->rest) && i->coeff.is_equal(_ex1)))) {
 519                                 // power::eval has such a rule, no need to handle powers here
 520                                 ++i;
 521                                 continue;
 522                         }
 523
 524                         // XXX: What is the best way to check if the polynomial is a primitive?
 525                         numeric c = i->rest.integer_content();
 526                         const numeric lead_coeff =
 527                                 ex_to<numeric>(ex_to<add>(i->rest).seq.begin()->coeff).div(c);
 528                         const bool canonicalizable = lead_coeff.is_integer();
 529
 530                         // XXX: The main variable is chosen in a random way, so this code
 531                         // does NOT transform the term into the canonical form (thus, in some
 532                         // very unlucky event it can even loop forever). Hopefully the main
 533                         // variable will be the same for all terms in *this
 534                         const bool unit_normal = lead_coeff.is_pos_integer();
 535                         if (likely((c == *_num1_p) && ((! canonicalizable) || unit_normal))) {
 536                                 ++i;
 537                                 continue;
 538                         }
 539
 540                         if (! something_changed) {
 541                                 s.reserve(seq_size);
 542                                 something_changed = true;
 543                         }
 544
 545                         while ((j!=i) && (j!=last)) {
 546                                 s.push_back(*j);
 547                                 ++j;
 548                         }
 549
 550                         if (! unit_normal)
 551                                 c = c.mul(*_num_1_p);
 552
 553                         oc = oc.mul(c);
 554
 555                         // divide add by the number in place to save at least 2 .eval() calls
 556                         const add& addref = ex_to<add>(i->rest);
 557                         add* primitive = new add(addref);
 558                         primitive->setflag(status_flags::dynallocated);
 559                         primitive->clearflag(status_flags::hash_calculated);
 560                         primitive->overall_coeff = ex_to<numeric>(primitive->overall_coeff).div_dyn(c);
 561                         for (epvector::iterator ai = primitive->seq.begin(); ai != primitive->seq.end(); ++ai)
 562                                 ai->coeff = ex_to<numeric>(ai->coeff).div_dyn(c);
 563
 564                         s.push_back(expair(*primitive, _ex1));
 565
 566                         ++i;
 567                         ++j;
 568                 }
 569                 if (something_changed) {
 570                         while (j!=last) {
 571                                 s.push_back(*j);
 572                                 ++j;
 573                         }
 574                         return (new mul(std::move(s), ex_to<numeric>(overall_coeff).mul_dyn(oc))
 575                                )->setflag(status_flags::dynallocated);
 576                 }
 577         }
 578
 579         return this->hold();
 580 }
 581
 582 ex mul::evalf(int level) const
 583 {
 584         if (level==1)
 585                 return mul(seq,overall_coeff);
 586
 587         if (level==-max_recursion_level)
 588                 throw(std::runtime_error("max recursion level reached"));
 589
 590         epvector s;
 591         s.reserve(seq.size());
 592
 593         --level;
 594         for (auto & it : seq) {
 595                 s.push_back(combine_ex_with_coeff_to_pair(it.rest.evalf(level),
 596                                                           it.coeff));
 597         }
 598         return mul(std::move(s), overall_coeff.evalf(level));
 599 }
 600
 601 void mul::find_real_imag(ex & rp, ex & ip) const
 602 {
 603         rp = overall_coeff.real_part();
 604         ip = overall_coeff.imag_part();
 605         for (auto & it : seq) {
 606                 ex factor = recombine_pair_to_ex(it);
 607                 ex new_rp = factor.real_part();
 608                 ex new_ip = factor.imag_part();
 609                 if (new_ip.is_zero()) {
 610                         rp *= new_rp;
 611                         ip *= new_rp;
 612                 } else {
 613                         ex temp = rp*new_rp - ip*new_ip;
 614                         ip = ip*new_rp + rp*new_ip;
 615                         rp = temp;
 616                 }
 617         }
 618         rp = rp.expand();
 619         ip = ip.expand();
 620 }
 621
 622 ex mul::real_part() const
 623 {
 624         ex rp, ip;
 625         find_real_imag(rp, ip);
 626         return rp;
 627 }
 628
 629 ex mul::imag_part() const
 630 {
 631         ex rp, ip;
 632         find_real_imag(rp, ip);
 633         return ip;
 634 }
 635
 636 ex mul::evalm() const
 637 {
 638         // numeric*matrix
 639         if (seq.size() == 1 && seq[0].coeff.is_equal(_ex1)
 640          && is_a<matrix>(seq[0].rest))
 641                 return ex_to<matrix>(seq[0].rest).mul(ex_to<numeric>(overall_coeff));
 642
 643         // Evaluate children first, look whether there are any matrices at all
 644         // (there can be either no matrices or one matrix; if there were more
 645         // than one matrix, it would be a non-commutative product)
 646         epvector s;
 647         s.reserve(seq.size());
 648
 649         bool have_matrix = false;
 650         epvector::iterator the_matrix;
 651
 652         for (auto & it : seq) {
 653                 const ex &m = recombine_pair_to_ex(it).evalm();
 654                 s.push_back(split_ex_to_pair(m));
 655                 if (is_a<matrix>(m)) {
 656                         have_matrix = true;
 657                         the_matrix = s.end() - 1;
 658                 }
 659         }
 660
 661         if (have_matrix) {
 662
 663                 // The product contained a matrix. We will multiply all other factors
 664                 // into that matrix.
 665                 matrix m = ex_to<matrix>(the_matrix->rest);
 666                 s.erase(the_matrix);
 667                 ex scalar = (new mul(std::move(s), overall_coeff))->setflag(status_flags::dynallocated);
 668                 return m.mul_scalar(scalar);
 669
 670         } else
 671                 return (new mul(std::move(s), overall_coeff))->setflag(status_flags::dynallocated);
 672 }
 673
 674 ex mul::eval_ncmul(const exvector & v) const
 675 {
 676         if (seq.empty())
 677                 return inherited::eval_ncmul(v);
 678
 679         // Find first noncommutative element and call its eval_ncmul()
 680         for (auto & it : seq)
 681                 if (it.rest.return_type() == return_types::noncommutative)
 682                         return it.rest.eval_ncmul(v);
 683         return inherited::eval_ncmul(v);
 684 }
 685
 686 bool tryfactsubs(const ex & origfactor, const ex & patternfactor, int & nummatches, exmap& repls)
 687 {
 688         ex origbase;
 689         int origexponent;
 690         int origexpsign;
 691
 692         if (is_exactly_a<power>(origfactor) && origfactor.op(1).info(info_flags::integer)) {
 693                 origbase = origfactor.op(0);
 694                 int expon = ex_to<numeric>(origfactor.op(1)).to_int();
 695                 origexponent = expon > 0 ? expon : -expon;
 696                 origexpsign = expon > 0 ? 1 : -1;
 697         } else {
 698                 origbase = origfactor;
 699                 origexponent = 1;
 700                 origexpsign = 1;
 701         }
 702
 703         ex patternbase;
 704         int patternexponent;
 705         int patternexpsign;
 706
 707         if (is_exactly_a<power>(patternfactor) && patternfactor.op(1).info(info_flags::integer)) {
 708                 patternbase = patternfactor.op(0);
 709                 int expon = ex_to<numeric>(patternfactor.op(1)).to_int();
 710                 patternexponent = expon > 0 ? expon : -expon;
 711                 patternexpsign = expon > 0 ? 1 : -1;
 712         } else {
 713                 patternbase = patternfactor;
 714                 patternexponent = 1;
 715                 patternexpsign = 1;
 716         }
 717
 718         exmap saverepls = repls;
 719         if (origexponent < patternexponent || origexpsign != patternexpsign || !origbase.match(patternbase,saverepls))
 720                 return false;
 721         repls = saverepls;
 722
 723         int newnummatches = origexponent / patternexponent;
 724         if (newnummatches < nummatches)
 725                 nummatches = newnummatches;
 726         return true;
 727 }
 728
 729 /** Checks whether e matches to the pattern pat and the (possibly to be updated)
 730   * list of replacements repls. This matching is in the sense of algebraic
 731   * substitutions. Matching starts with pat.op(factor) of the pattern because
 732   * the factors before this one have already been matched. The (possibly
 733   * updated) number of matches is in nummatches. subsed[i] is true for factors
 734   * that already have been replaced by previous substitutions and matched[i]
 735   * is true for factors that have been matched by the current match.
 736   */
 737 bool algebraic_match_mul_with_mul(const mul &e, const ex &pat, exmap& repls,
 738                                   int factor, int &nummatches, const std::vector<bool> &subsed,
 739                                   std::vector<bool> &matched)
 740 {
 741         GINAC_ASSERT(subsed.size() == e.nops());
 742         GINAC_ASSERT(matched.size() == e.nops());
 743
 744         if (factor == (int)pat.nops())
 745                 return true;
 746
 747         for (size_t i=0; i<e.nops(); ++i) {
 748                 if(subsed[i] || matched[i])
 749                         continue;
 750                 exmap newrepls = repls;
 751                 int newnummatches = nummatches;
 752                 if (tryfactsubs(e.op(i), pat.op(factor), newnummatches, newrepls)) {
 753                         matched[i] = true;
 754                         if (algebraic_match_mul_with_mul(e, pat, newrepls, factor+1,
 755                                         newnummatches, subsed, matched)) {
 756                                 repls = newrepls;
 757                                 nummatches = newnummatches;
 758                                 return true;
 759                         }
 760                         else
 761                                 matched[i] = false;
 762                 }
 763         }
 764
 765         return false;
 766 }
 767
 768 bool mul::has(const ex & pattern, unsigned options) const
 769 {
 770         if(!(options & has_options::algebraic))
 771                 return basic::has(pattern,options);
 772         if(is_a<mul>(pattern)) {
 773                 exmap repls;
 774                 int nummatches = std::numeric_limits<int>::max();
 775                 std::vector<bool> subsed(nops(), false);
 776                 std::vector<bool> matched(nops(), false);
 777                 if(algebraic_match_mul_with_mul(*this, pattern, repls, 0, nummatches,
 778                                 subsed, matched))
 779                         return true;
 780         }
 781         return basic::has(pattern, options);
 782 }
 783
 784 ex mul::algebraic_subs_mul(const exmap & m, unsigned options) const
 785 {
 786         std::vector<bool> subsed(nops(), false);
 787         ex divide_by = 1;
 788         ex multiply_by = 1;
 789
 790         for (auto & it : m) {
 791
 792                 if (is_exactly_a<mul>(it.first)) {
 793 retry1:
 794                         int nummatches = std::numeric_limits<int>::max();
 795                         std::vector<bool> currsubsed(nops(), false);
 796                         exmap repls;
 797
 798                         if (!algebraic_match_mul_with_mul(*this, it.first, repls, 0, nummatches, subsed, currsubsed))
 799                                 continue;
 800
 801                         for (size_t j=0; j<subsed.size(); j++)
 802                                 if (currsubsed[j])
 803                                         subsed[j] = true;
 804                         ex subsed_pattern
 805                                 = it.first.subs(repls, subs_options::no_pattern);
 806                         divide_by *= power(subsed_pattern, nummatches);
 807                         ex subsed_result
 808                                 = it.second.subs(repls, subs_options::no_pattern);
 809                         multiply_by *= power(subsed_result, nummatches);
 810                         goto retry1;
 811
 812                 } else {
 813
 814                         for (size_t j=0; j<this->nops(); j++) {
 815                                 int nummatches = std::numeric_limits<int>::max();
 816                                 exmap repls;
 817                                 if (!subsed[j] && tryfactsubs(op(j), it.first, nummatches, repls)){
 818                                         subsed[j] = true;
 819                                         ex subsed_pattern
 820                                                 = it.first.subs(repls, subs_options::no_pattern);
 821                                         divide_by *= power(subsed_pattern, nummatches);
 822                                         ex subsed_result
 823                                                 = it.second.subs(repls, subs_options::no_pattern);
 824                                         multiply_by *= power(subsed_result, nummatches);
 825                                 }
 826                         }
 827                 }
 828         }
 829
 830         bool subsfound = false;
 831         for (size_t i=0; i<subsed.size(); i++) {
 832                 if (subsed[i]) {
 833                         subsfound = true;
 834                         break;
 835                 }
 836         }
 837         if (!subsfound)
 838                 return subs_one_level(m, options | subs_options::algebraic);
 839
 840         return ((*this)/divide_by)*multiply_by;
 841 }
 842
 843 ex mul::conjugate() const
 844 {
 845         // The base class' method is wrong here because we have to be careful at
 846         // branch cuts. power::conjugate takes care of that already, so use it.
 847         std::unique_ptr<epvector> newepv(nullptr);
 848         for (auto i=seq.begin(); i!=seq.end(); ++i) {
 849                 if (newepv) {
 850                         newepv->push_back(split_ex_to_pair(recombine_pair_to_ex(*i).conjugate()));
 851                         continue;
 852                 }
 853                 ex x = recombine_pair_to_ex(*i);
 854                 ex c = x.conjugate();
 855                 if (c.is_equal(x)) {
 856                         continue;
 857                 }
 858                 newepv.reset(new epvector);
 859                 newepv->reserve(seq.size());
 860                 for (auto j=seq.begin(); j!=i; ++j) {
 861                         newepv->push_back(*j);
 862                 }
 863                 newepv->push_back(split_ex_to_pair(c));
 864         }
 865         ex x = overall_coeff.conjugate();
 866         if (!newepv && are_ex_trivially_equal(x, overall_coeff)) {
 867                 return *this;
 868         }
 869         return thisexpairseq(newepv ? std::move(*newepv) : seq, x);
 870 }
 871
 872
 873 // protected
 874
 875 /** Implementation of ex::diff() for a product.  It applies the product rule.
 876  *  @see ex::diff */
 877 ex mul::derivative(const symbol & s) const
 878 {
 879         size_t num = seq.size();
 880         exvector addseq;
 881         addseq.reserve(num);
 882
 883         // D(a*b*c) = D(a)*b*c + a*D(b)*c + a*b*D(c)
 884         epvector mulseq = seq;
 885         auto i = seq.begin(), end = seq.end();
 886         auto i2 = mulseq.begin();
 887         while (i != end) {
 888                 expair ep = split_ex_to_pair(power(i->rest, i->coeff - _ex1) *
 889                                              i->rest.diff(s));
 890                 ep.swap(*i2);
 891                 addseq.push_back((new mul(mulseq, overall_coeff * i->coeff))->setflag(status_flags::dynallocated));
 892                 ep.swap(*i2);
 893                 ++i; ++i2;
 894         }
 895         return (new add(addseq))->setflag(status_flags::dynallocated);
 896 }
 897
 898 int mul::compare_same_type(const basic & other) const
 899 {
 900         return inherited::compare_same_type(other);
 901 }
 902
 903 unsigned mul::return_type() const
 904 {
 905         if (seq.empty()) {
 906                 // mul without factors: should not happen, but commutates
 907                 return return_types::commutative;
 908         }
 909
 910         bool all_commutative = true;
 911         epvector::const_iterator noncommutative_element; // point to first found nc element
 912
 913         epvector::const_iterator i = seq.begin(), end = seq.end();
 914         while (i != end) {
 915                 unsigned rt = i->rest.return_type();
 916                 if (rt == return_types::noncommutative_composite)
 917                         return rt; // one ncc -> mul also ncc
 918                 if ((rt == return_types::noncommutative) && (all_commutative)) {
 919                         // first nc element found, remember position
 920                         noncommutative_element = i;
 921                         all_commutative = false;
 922                 }
 923                 if ((rt == return_types::noncommutative) && (!all_commutative)) {
 924                         // another nc element found, compare type_infos
 925                         if (noncommutative_element->rest.return_type_tinfo() != i->rest.return_type_tinfo()) {
 926                                         // different types -> mul is ncc
 927                                         return return_types::noncommutative_composite;
 928                         }
 929                 }
 930                 ++i;
 931         }
 932         // all factors checked
 933         return all_commutative ? return_types::commutative : return_types::noncommutative;
 934 }
 935
 936 return_type_t mul::return_type_tinfo() const
 937 {
 938         if (seq.empty())
 939                 return make_return_type_t<mul>(); // mul without factors: should not happen
 940
 941         // return type_info of first noncommutative element
 942         for (auto & it : seq)
 943                 if (it.rest.return_type() == return_types::noncommutative)
 944                         return it.rest.return_type_tinfo();
 945
 946         // no noncommutative element found, should not happen
 947         return make_return_type_t<mul>();
 948 }
 949
 950 ex mul::thisexpairseq(const epvector & v, const ex & oc, bool do_index_renaming) const
 951 {
 952         return (new mul(v, oc, do_index_renaming))->setflag(status_flags::dynallocated);
 953 }
 954
 955 ex mul::thisexpairseq(epvector && vp, const ex & oc, bool do_index_renaming) const
 956 {
 957         return (new mul(std::move(vp), oc, do_index_renaming))->setflag(status_flags::dynallocated);
 958 }
 959
 960 expair mul::split_ex_to_pair(const ex & e) const
 961 {
 962         if (is_exactly_a<power>(e)) {
 963                 const power & powerref = ex_to<power>(e);
 964                 if (is_exactly_a<numeric>(powerref.exponent))
 965                         return expair(powerref.basis,powerref.exponent);
 966         }
 967         return expair(e,_ex1);
 968 }
 969
 970 expair mul::combine_ex_with_coeff_to_pair(const ex & e,
 971                                           const ex & c) const
 972 {
 973         // to avoid duplication of power simplification rules,
 974         // we create a temporary power object
 975         // otherwise it would be hard to correctly evaluate
 976         // expression like (4^(1/3))^(3/2)
 977         if (c.is_equal(_ex1))
 978                 return split_ex_to_pair(e);
 979
 980         return split_ex_to_pair(power(e,c));
 981 }
 982
 983 expair mul::combine_pair_with_coeff_to_pair(const expair & p,
 984                                             const ex & c) const
 985 {
 986         // to avoid duplication of power simplification rules,
 987         // we create a temporary power object
 988         // otherwise it would be hard to correctly evaluate
 989         // expression like (4^(1/3))^(3/2)
 990         if (c.is_equal(_ex1))
 991                 return p;
 992
 993         return split_ex_to_pair(power(recombine_pair_to_ex(p),c));
 994 }
 995
 996 ex mul::recombine_pair_to_ex(const expair & p) const
 997 {
 998         if (ex_to<numeric>(p.coeff).is_equal(*_num1_p))
 999                 return p.rest;
1000         else
1001                 return (new power(p.rest,p.coeff))->setflag(status_flags::dynallocated);
1002 }
1003
1004 bool mul::expair_needs_further_processing(epp it)
1005 {
1006         if (is_exactly_a<mul>(it->rest) &&
1007             ex_to<numeric>(it->coeff).is_integer()) {
1008                 // combined pair is product with integer power -> expand it
1009                 *it = split_ex_to_pair(recombine_pair_to_ex(*it));
1010                 return true;
1011         }
1012         if (is_exactly_a<numeric>(it->rest)) {
1013                 if (it->coeff.is_equal(_ex1)) {
1014                         // pair has coeff 1 and must be moved to the end
1015                         return true;
1016                 }
1017                 expair ep = split_ex_to_pair(recombine_pair_to_ex(*it));
1018                 if (!ep.is_equal(*it)) {
1019                         // combined pair is a numeric power which can be simplified
1020                         *it = ep;
1021                         return true;
1022                 }
1023         }
1024         return false;
1025 }
1026
1027 ex mul::default_overall_coeff() const
1028 {
1029         return _ex1;
1030 }
1031
1032 void mul::combine_overall_coeff(const ex & c)
1033 {
1034         GINAC_ASSERT(is_exactly_a<numeric>(overall_coeff));
1035         GINAC_ASSERT(is_exactly_a<numeric>(c));
1036         overall_coeff = ex_to<numeric>(overall_coeff).mul_dyn(ex_to<numeric>(c));
1037 }
1038
1039 void mul::combine_overall_coeff(const ex & c1, const ex & c2)
1040 {
1041         GINAC_ASSERT(is_exactly_a<numeric>(overall_coeff));
1042         GINAC_ASSERT(is_exactly_a<numeric>(c1));
1043         GINAC_ASSERT(is_exactly_a<numeric>(c2));
1044         overall_coeff = ex_to<numeric>(overall_coeff).mul_dyn(ex_to<numeric>(c1).power(ex_to<numeric>(c2)));
1045 }
1046
1047 bool mul::can_make_flat(const expair & p) const
1048 {
1049         GINAC_ASSERT(is_exactly_a<numeric>(p.coeff));
1050
1051         // (x*y)^c == x^c*y^c  if c ∈ ℤ
1052         return p.coeff.info(info_flags::integer);
1053 }
1054
1055 bool mul::can_be_further_expanded(const ex & e)
1056 {
1057         if (is_exactly_a<mul>(e)) {
1058                 for (auto & it : ex_to<mul>(e).seq) {
1059                         if (is_exactly_a<add>(it.rest) && it.coeff.info(info_flags::posint))
1060                                 return true;
1061                 }
1062         } else if (is_exactly_a<power>(e)) {
1063                 if (is_exactly_a<add>(e.op(0)) && e.op(1).info(info_flags::posint))
1064                         return true;
1065         }
1066         return false;
1067 }
1068
1069 ex mul::expand(unsigned options) const
1070 {
1071         {
1072         // trivial case: expanding the monomial (~ 30% of all calls)
1073                 epvector::const_iterator i = seq.begin(), seq_end = seq.end();
1074                 while ((i != seq.end()) &&  is_a<symbol>(i->rest) && i->coeff.info(info_flags::integer))
1075                         ++i;
1076                 if (i == seq_end) {
1077                         setflag(status_flags::expanded);
1078                         return *this;
1079                 }
1080         }
1081
1082         // do not rename indices if the object has no indices at all
1083         if ((!(options & expand_options::expand_rename_idx)) &&
1084                         this->info(info_flags::has_indices))
1085                 options |= expand_options::expand_rename_idx;
1086
1087         const bool skip_idx_rename = !(options & expand_options::expand_rename_idx);
1088
1089         // First, expand the children
1090         epvector expanded = expandchildren(options);
1091         const epvector & expanded_seq = (expanded.empty() ? seq : expanded);
1092
1093         // Now, look for all the factors that are sums and multiply each one out
1094         // with the next one that is found while collecting the factors which are
1095         // not sums
1096         ex last_expanded = _ex1;
1097
1098         epvector non_adds;
1099         non_adds.reserve(expanded_seq.size());
1100
1101         for (const auto & cit : expanded_seq) {
1102                 if (is_exactly_a<add>(cit.rest) &&
1103                         (cit.coeff.is_equal(_ex1))) {
1104                         if (is_exactly_a<add>(last_expanded)) {
1105
1106                                 // Expand a product of two sums, aggressive version.
1107                                 // Caring for the overall coefficients in separate loops can
1108                                 // sometimes give a performance gain of up to 15%!
1109
1110                                 const int sizedifference = ex_to<add>(last_expanded).seq.size()-ex_to<add>(cit.rest).seq.size();
1111                                 // add2 is for the inner loop and should be the bigger of the two sums
1112                                 // in the presence of asymptotically good sorting:
1113                                 const add& add1 = (sizedifference<0 ? ex_to<add>(last_expanded) : ex_to<add>(cit.rest));
1114                                 const add& add2 = (sizedifference<0 ? ex_to<add>(cit.rest) : ex_to<add>(last_expanded));
1115                                 epvector distrseq;
1116                                 distrseq.reserve(add1.seq.size()+add2.seq.size());
1117
1118                                 // Multiply add2 with the overall coefficient of add1 and append it to distrseq:
1119                                 if (!add1.overall_coeff.is_zero()) {
1120                                         if (add1.overall_coeff.is_equal(_ex1))
1121                                                 distrseq.insert(distrseq.end(), add2.seq.begin(), add2.seq.end());
1122                                         else
1123                                                 for (const auto & i : add2.seq)
1124                                                         distrseq.push_back(expair(i.rest, ex_to<numeric>(i.coeff).mul_dyn(ex_to<numeric>(add1.overall_coeff))));
1125                                 }
1126
1127                                 // Multiply add1 with the overall coefficient of add2 and append it to distrseq:
1128                                 if (!add2.overall_coeff.is_zero()) {
1129                                         if (add2.overall_coeff.is_equal(_ex1))
1130                                                 distrseq.insert(distrseq.end(), add1.seq.begin(), add1.seq.end());
1131                                         else
1132                                                 for (const auto & i : add1.seq)
1133                                                         distrseq.push_back(expair(i.rest, ex_to<numeric>(i.coeff).mul_dyn(ex_to<numeric>(add2.overall_coeff))));
1134                                 }
1135
1136                                 // Compute the new overall coefficient and put it together:
1137                                 ex tmp_accu = (new add(distrseq, add1.overall_coeff*add2.overall_coeff))->setflag(status_flags::dynallocated);
1138
1139                                 exvector add1_dummy_indices, add2_dummy_indices, add_indices;
1140                                 lst dummy_subs;
1141
1142                                 if (!skip_idx_rename) {
1143                                         for (const auto & i : add1.seq) {
1144                                                 add_indices = get_all_dummy_indices_safely(i.rest);
1145                                                 add1_dummy_indices.insert(add1_dummy_indices.end(), add_indices.begin(), add_indices.end());
1146                                         }
1147                                         for (const auto & i : add2.seq) {
1148                                                 add_indices = get_all_dummy_indices_safely(i.rest);
1149                                                 add2_dummy_indices.insert(add2_dummy_indices.end(), add_indices.begin(), add_indices.end());
1150                                         }
1151
1152                                         sort(add1_dummy_indices.begin(), add1_dummy_indices.end(), ex_is_less());
1153                                         sort(add2_dummy_indices.begin(), add2_dummy_indices.end(), ex_is_less());
1154                                         dummy_subs = rename_dummy_indices_uniquely(add1_dummy_indices, add2_dummy_indices);
1155                                 }
1156
1157                                 // Multiply explicitly all non-numeric terms of add1 and add2:
1158                                 for (const auto & i2 : add2.seq) {
1159                                         // We really have to combine terms here in order to compactify
1160                                         // the result.  Otherwise it would become waayy tooo bigg.
1161                                         numeric oc(*_num0_p);
1162                                         epvector distrseq2;
1163                                         distrseq2.reserve(add1.seq.size());
1164                                         const ex i2_new = (skip_idx_rename || (dummy_subs.op(0).nops() == 0) ?
1165                                                         i2.rest :
1166                                                         i2.rest.subs(ex_to<lst>(dummy_subs.op(0)),
1167                                                                      ex_to<lst>(dummy_subs.op(1)), subs_options::no_pattern));
1168                                         for (const auto & i1 : add1.seq) {
1169                                                 // Don't push_back expairs which might have a rest that evaluates to a numeric,
1170                                                 // since that would violate an invariant of expairseq:
1171                                                 const ex rest = (new mul(i1.rest, i2_new))->setflag(status_flags::dynallocated);
1172                                                 if (is_exactly_a<numeric>(rest)) {
1173                                                         oc += ex_to<numeric>(rest).mul(ex_to<numeric>(i1.coeff).mul(ex_to<numeric>(i2.coeff)));
1174                                                 } else {
1175                                                         distrseq2.push_back(expair(rest, ex_to<numeric>(i1.coeff).mul_dyn(ex_to<numeric>(i2.coeff))));
1176                                                 }
1177                                         }
1178                                         tmp_accu += (new add(distrseq2, oc))->setflag(status_flags::dynallocated);
1179                                 }
1180                                 last_expanded = tmp_accu;
1181                         } else {
1182                                 if (!last_expanded.is_equal(_ex1))
1183                                         non_adds.push_back(split_ex_to_pair(last_expanded));
1184                                 last_expanded = cit.rest;
1185                         }
1186
1187                 } else {
1188                         non_adds.push_back(cit);
1189                 }
1190         }
1191
1192         // Now the only remaining thing to do is to multiply the factors which
1193         // were not sums into the "last_expanded" sum
1194         if (is_exactly_a<add>(last_expanded)) {
1195                 size_t n = last_expanded.nops();
1196                 exvector distrseq;
1197                 distrseq.reserve(n);
1198                 exvector va;
1199                 if (! skip_idx_rename) {
1200                         va = get_all_dummy_indices_safely(mul(non_adds));
1201                         sort(va.begin(), va.end(), ex_is_less());
1202                 }
1203
1204                 for (size_t i=0; i<n; ++i) {
1205                         epvector factors = non_adds;
1206                         if (skip_idx_rename)
1207                                 factors.push_back(split_ex_to_pair(last_expanded.op(i)));
1208                         else
1209                                 factors.push_back(split_ex_to_pair(rename_dummy_indices_uniquely(va, last_expanded.op(i))));
1210                         ex term = (new mul(factors, overall_coeff))->setflag(status_flags::dynallocated);
1211                         if (can_be_further_expanded(term)) {
1212                                 distrseq.push_back(term.expand());
1213                         } else {
1214                                 if (options == 0)
1215                                         ex_to<basic>(term).setflag(status_flags::expanded);
1216                                 distrseq.push_back(term);
1217                         }
1218                 }
1219
1220                 return ((new add(distrseq))->
1221                         setflag(status_flags::dynallocated | (options == 0 ? status_flags::expanded : 0)));
1222         }
1223
1224         non_adds.push_back(split_ex_to_pair(last_expanded));
1225         ex result = (new mul(non_adds, overall_coeff))->setflag(status_flags::dynallocated);
1226         if (can_be_further_expanded(result)) {
1227                 return result.expand();
1228         } else {
1229                 if (options == 0)
1230                         ex_to<basic>(result).setflag(status_flags::expanded);
1231                 return result;
1232         }
1233 }
1234
1235
1236 //////////
1237 // new virtual functions which can be overridden by derived classes
1238 //////////
1239
1240 // none
1241
1242 //////////
1243 // non-virtual functions in this class
1244 //////////
1245
1246
1247 /** Member-wise expand the expairs representing this sequence.  This must be
1248  *  overridden from expairseq::expandchildren() and done iteratively in order
1249  *  to allow for early cancellations and thus safe memory.
1250  *
1251  *  @see mul::expand()
1252  *  @return epvector containing expanded pairs, empty if no members
1253  *    had to be changed. */
1254 epvector mul::expandchildren(unsigned options) const
1255 {
1256         auto cit = seq.begin(), last = seq.end();
1257         while (cit!=last) {
1258                 const ex & factor = recombine_pair_to_ex(*cit);
1259                 const ex & expanded_factor = factor.expand(options);
1260                 if (!are_ex_trivially_equal(factor,expanded_factor)) {
1261
1262                         // something changed, copy seq, eval and return it
1263                         epvector s;
1264                         s.reserve(seq.size());
1265
1266                         // copy parts of seq which are known not to have changed
1267                         auto cit2 = seq.begin();
1268                         while (cit2!=cit) {
1269                                 s.push_back(*cit2);
1270                                 ++cit2;
1271                         }
1272
1273                         // copy first changed element
1274                         s.push_back(split_ex_to_pair(expanded_factor));
1275                         ++cit2;
1276
1277                         // copy rest
1278                         while (cit2!=last) {
1279                                 s.push_back(split_ex_to_pair(recombine_pair_to_ex(*cit2).expand(options)));
1280                                 ++cit2;
1281                         }
1282                         return s;
1283                 }
1284                 ++cit;
1285         }
1286
1287         return epvector(); // nothing has changed
1288 }
1289
1290 GINAC_BIND_UNARCHIVER(mul);
1291
1292 } // namespace GiNaC