ginac/mul.cpp

   1 /** @file mul.cpp
   2  *
   3  *  Implementation of GiNaC's products of expressions. */
   4
   5 /*
   6  *  GiNaC Copyright (C) 1999-2005 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 <iostream>
  24 #include <vector>
  25 #include <stdexcept>
  26 #include <limits>
  27
  28 #include "mul.h"
  29 #include "add.h"
  30 #include "power.h"
  31 #include "operators.h"
  32 #include "matrix.h"
  33 #include "indexed.h"
  34 #include "lst.h"
  35 #include "archive.h"
  36 #include "utils.h"
  37
  38 namespace GiNaC {
  39
  40 GINAC_IMPLEMENT_REGISTERED_CLASS_OPT(mul, expairseq,
  41   print_func<print_context>(&mul::do_print).
  42   print_func<print_latex>(&mul::do_print_latex).
  43   print_func<print_csrc>(&mul::do_print_csrc).
  44   print_func<print_tree>(&mul::do_print_tree).
  45   print_func<print_python_repr>(&mul::do_print_python_repr))
  46
  47
  48 //////////
  49 // default constructor
  50 //////////
  51
  52 mul::mul()
  53 {
  54         tinfo_key = TINFO_mul;
  55 }
  56
  57 //////////
  58 // other constructors
  59 //////////
  60
  61 // public
  62
  63 mul::mul(const ex & lh, const ex & rh)
  64 {
  65         tinfo_key = TINFO_mul;
  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         tinfo_key = TINFO_mul;
  74         overall_coeff = _ex1;
  75         construct_from_exvector(v);
  76         GINAC_ASSERT(is_canonical());
  77 }
  78
  79 mul::mul(const epvector & v)
  80 {
  81         tinfo_key = TINFO_mul;
  82         overall_coeff = _ex1;
  83         construct_from_epvector(v);
  84         GINAC_ASSERT(is_canonical());
  85 }
  86
  87 mul::mul(const epvector & v, const ex & oc)
  88 {
  89         tinfo_key = TINFO_mul;
  90         overall_coeff = oc;
  91         construct_from_epvector(v);
  92         GINAC_ASSERT(is_canonical());
  93 }
  94
  95 mul::mul(std::auto_ptr<epvector> vp, const ex & oc)
  96 {
  97         tinfo_key = TINFO_mul;
  98         GINAC_ASSERT(vp.get()!=0);
  99         overall_coeff = oc;
 100         construct_from_epvector(*vp);
 101         GINAC_ASSERT(is_canonical());
 102 }
 103
 104 mul::mul(const ex & lh, const ex & mh, const ex & rh)
 105 {
 106         tinfo_key = TINFO_mul;
 107         exvector factors;
 108         factors.reserve(3);
 109         factors.push_back(lh);
 110         factors.push_back(mh);
 111         factors.push_back(rh);
 112         overall_coeff = _ex1;
 113         construct_from_exvector(factors);
 114         GINAC_ASSERT(is_canonical());
 115 }
 116
 117 //////////
 118 // archiving
 119 //////////
 120
 121 DEFAULT_ARCHIVING(mul)
 122
 123 //////////
 124 // functions overriding virtual functions from base classes
 125 //////////
 126
 127 void mul::print_overall_coeff(const print_context & c, const char *mul_sym) const
 128 {
 129         const numeric &coeff = ex_to<numeric>(overall_coeff);
 130         if (coeff.csgn() == -1)
 131                 c.s << '-';
 132         if (!coeff.is_equal(*_num1_p) &&
 133                 !coeff.is_equal(*_num_1_p)) {
 134                 if (coeff.is_rational()) {
 135                         if (coeff.is_negative())
 136                                 (-coeff).print(c);
 137                         else
 138                                 coeff.print(c);
 139                 } else {
 140                         if (coeff.csgn() == -1)
 141                                 (-coeff).print(c, precedence());
 142                         else
 143                                 coeff.print(c, precedence());
 144                 }
 145                 c.s << mul_sym;
 146         }
 147 }
 148
 149 void mul::do_print(const print_context & c, unsigned level) const
 150 {
 151         if (precedence() <= level)
 152                 c.s << '(';
 153
 154         print_overall_coeff(c, "*");
 155
 156         epvector::const_iterator it = seq.begin(), itend = seq.end();
 157         bool first = true;
 158         while (it != itend) {
 159                 if (!first)
 160                         c.s << '*';
 161                 else
 162                         first = false;
 163                 recombine_pair_to_ex(*it).print(c, precedence());
 164                 ++it;
 165         }
 166
 167         if (precedence() <= level)
 168                 c.s << ')';
 169 }
 170
 171 void mul::do_print_latex(const print_latex & c, unsigned level) const
 172 {
 173         if (precedence() <= level)
 174                 c.s << "{(";
 175
 176         print_overall_coeff(c, " ");
 177
 178         // Separate factors into those with negative numeric exponent
 179         // and all others
 180         epvector::const_iterator it = seq.begin(), itend = seq.end();
 181         exvector neg_powers, others;
 182         while (it != itend) {
 183                 GINAC_ASSERT(is_exactly_a<numeric>(it->coeff));
 184                 if (ex_to<numeric>(it->coeff).is_negative())
 185                         neg_powers.push_back(recombine_pair_to_ex(expair(it->rest, -(it->coeff))));
 186                 else
 187                         others.push_back(recombine_pair_to_ex(*it));
 188                 ++it;
 189         }
 190
 191         if (!neg_powers.empty()) {
 192
 193                 // Factors with negative exponent are printed as a fraction
 194                 c.s << "\\frac{";
 195                 mul(others).eval().print(c);
 196                 c.s << "}{";
 197                 mul(neg_powers).eval().print(c);
 198                 c.s << "}";
 199
 200         } else {
 201
 202                 // All other factors are printed in the ordinary way
 203                 exvector::const_iterator vit = others.begin(), vitend = others.end();
 204                 while (vit != vitend) {
 205                         c.s << ' ';
 206                         vit->print(c, precedence());
 207                         ++vit;
 208                 }
 209         }
 210
 211         if (precedence() <= level)
 212                 c.s << ")}";
 213 }
 214
 215 void mul::do_print_csrc(const print_csrc & c, unsigned level) const
 216 {
 217         if (precedence() <= level)
 218                 c.s << "(";
 219
 220         if (!overall_coeff.is_equal(_ex1)) {
 221                 overall_coeff.print(c, precedence());
 222                 c.s << "*";
 223         }
 224
 225         // Print arguments, separated by "*" or "/"
 226         epvector::const_iterator it = seq.begin(), itend = seq.end();
 227         while (it != itend) {
 228
 229                 // If the first argument is a negative integer power, it gets printed as "1.0/<expr>"
 230                 bool needclosingparenthesis = false;
 231                 if (it == seq.begin() && it->coeff.info(info_flags::negint)) {
 232                         if (is_a<print_csrc_cl_N>(c)) {
 233                                 c.s << "recip(";
 234                                 needclosingparenthesis = true;
 235                         } else
 236                                 c.s << "1.0/";
 237                 }
 238
 239                 // If the exponent is 1 or -1, it is left out
 240                 if (it->coeff.is_equal(_ex1) || it->coeff.is_equal(_ex_1))
 241                         it->rest.print(c, precedence());
 242                 else if (it->coeff.info(info_flags::negint))
 243                         // Outer parens around ex needed for broken GCC parser:
 244                         (ex(power(it->rest, -ex_to<numeric>(it->coeff)))).print(c, level);
 245                 else
 246                         // Outer parens around ex needed for broken GCC parser:
 247                         (ex(power(it->rest, ex_to<numeric>(it->coeff)))).print(c, level);
 248
 249                 if (needclosingparenthesis)
 250                         c.s << ")";
 251
 252                 // Separator is "/" for negative integer powers, "*" otherwise
 253                 ++it;
 254                 if (it != itend) {
 255                         if (it->coeff.info(info_flags::negint))
 256                                 c.s << "/";
 257                         else
 258                                 c.s << "*";
 259                 }
 260         }
 261
 262         if (precedence() <= level)
 263                 c.s << ")";
 264 }
 265
 266 void mul::do_print_python_repr(const print_python_repr & c, unsigned level) const
 267 {
 268         c.s << class_name() << '(';
 269         op(0).print(c);
 270         for (size_t i=1; i<nops(); ++i) {
 271                 c.s << ',';
 272                 op(i).print(c);
 273         }
 274         c.s << ')';
 275 }
 276
 277 bool mul::info(unsigned inf) const
 278 {
 279         switch (inf) {
 280                 case info_flags::polynomial:
 281                 case info_flags::integer_polynomial:
 282                 case info_flags::cinteger_polynomial:
 283                 case info_flags::rational_polynomial:
 284                 case info_flags::crational_polynomial:
 285                 case info_flags::rational_function: {
 286                         epvector::const_iterator i = seq.begin(), end = seq.end();
 287                         while (i != end) {
 288                                 if (!(recombine_pair_to_ex(*i).info(inf)))
 289                                         return false;
 290                                 ++i;
 291                         }
 292                         return overall_coeff.info(inf);
 293                 }
 294                 case info_flags::algebraic: {
 295                         epvector::const_iterator i = seq.begin(), end = seq.end();
 296                         while (i != end) {
 297                                 if ((recombine_pair_to_ex(*i).info(inf)))
 298                                         return true;
 299                                 ++i;
 300                         }
 301                         return false;
 302                 }
 303         }
 304         return inherited::info(inf);
 305 }
 306
 307 int mul::degree(const ex & s) const
 308 {
 309         // Sum up degrees of factors
 310         int deg_sum = 0;
 311         epvector::const_iterator i = seq.begin(), end = seq.end();
 312         while (i != end) {
 313                 if (ex_to<numeric>(i->coeff).is_integer())
 314                         deg_sum += i->rest.degree(s) * ex_to<numeric>(i->coeff).to_int();
 315                 ++i;
 316         }
 317         return deg_sum;
 318 }
 319
 320 int mul::ldegree(const ex & s) const
 321 {
 322         // Sum up degrees of factors
 323         int deg_sum = 0;
 324         epvector::const_iterator i = seq.begin(), end = seq.end();
 325         while (i != end) {
 326                 if (ex_to<numeric>(i->coeff).is_integer())
 327                         deg_sum += i->rest.ldegree(s) * ex_to<numeric>(i->coeff).to_int();
 328                 ++i;
 329         }
 330         return deg_sum;
 331 }
 332
 333 ex mul::coeff(const ex & s, int n) const
 334 {
 335         exvector coeffseq;
 336         coeffseq.reserve(seq.size()+1);
 337
 338         if (n==0) {
 339                 // product of individual coeffs
 340                 // if a non-zero power of s is found, the resulting product will be 0
 341                 epvector::const_iterator i = seq.begin(), end = seq.end();
 342                 while (i != end) {
 343                         coeffseq.push_back(recombine_pair_to_ex(*i).coeff(s,n));
 344                         ++i;
 345                 }
 346                 coeffseq.push_back(overall_coeff);
 347                 return (new mul(coeffseq))->setflag(status_flags::dynallocated);
 348         }
 349
 350         epvector::const_iterator i = seq.begin(), end = seq.end();
 351         bool coeff_found = false;
 352         while (i != end) {
 353                 ex t = recombine_pair_to_ex(*i);
 354                 ex c = t.coeff(s, n);
 355                 if (!c.is_zero()) {
 356                         coeffseq.push_back(c);
 357                         coeff_found = 1;
 358                 } else {
 359                         coeffseq.push_back(t);
 360                 }
 361                 ++i;
 362         }
 363         if (coeff_found) {
 364                 coeffseq.push_back(overall_coeff);
 365                 return (new mul(coeffseq))->setflag(status_flags::dynallocated);
 366         }
 367
 368         return _ex0;
 369 }
 370
 371 /** Perform automatic term rewriting rules in this class.  In the following
 372  *  x, x1, x2,... stand for a symbolic variables of type ex and c, c1, c2...
 373  *  stand for such expressions that contain a plain number.
 374  *  - *(...,x;0) -> 0
 375  *  - *(+(x1,x2,...);c) -> *(+(*(x1,c),*(x2,c),...))
 376  *  - *(x;1) -> x
 377  *  - *(;c) -> c
 378  *
 379  *  @param level cut-off in recursive evaluation */
 380 ex mul::eval(int level) const
 381 {
 382         std::auto_ptr<epvector> evaled_seqp = evalchildren(level);
 383         if (evaled_seqp.get()) {
 384                 // do more evaluation later
 385                 return (new mul(evaled_seqp, overall_coeff))->
 386                            setflag(status_flags::dynallocated);
 387         }
 388
 389 #ifdef DO_GINAC_ASSERT
 390         epvector::const_iterator i = seq.begin(), end = seq.end();
 391         while (i != end) {
 392                 GINAC_ASSERT((!is_exactly_a<mul>(i->rest)) ||
 393                              (!(ex_to<numeric>(i->coeff).is_integer())));
 394                 GINAC_ASSERT(!(i->is_canonical_numeric()));
 395                 if (is_exactly_a<numeric>(recombine_pair_to_ex(*i)))
 396                     print(print_tree(std::cerr));
 397                 GINAC_ASSERT(!is_exactly_a<numeric>(recombine_pair_to_ex(*i)));
 398                 /* for paranoia */
 399                 expair p = split_ex_to_pair(recombine_pair_to_ex(*i));
 400                 GINAC_ASSERT(p.rest.is_equal(i->rest));
 401                 GINAC_ASSERT(p.coeff.is_equal(i->coeff));
 402                 /* end paranoia */
 403                 ++i;
 404         }
 405 #endif // def DO_GINAC_ASSERT
 406
 407         if (flags & status_flags::evaluated) {
 408                 GINAC_ASSERT(seq.size()>0);
 409                 GINAC_ASSERT(seq.size()>1 || !overall_coeff.is_equal(_ex1));
 410                 return *this;
 411         }
 412
 413         int seq_size = seq.size();
 414         if (overall_coeff.is_zero()) {
 415                 // *(...,x;0) -> 0
 416                 return _ex0;
 417         } else if (seq_size==0) {
 418                 // *(;c) -> c
 419                 return overall_coeff;
 420         } else if (seq_size==1 && overall_coeff.is_equal(_ex1)) {
 421                 // *(x;1) -> x
 422                 return recombine_pair_to_ex(*(seq.begin()));
 423         } else if ((seq_size==1) &&
 424                    is_exactly_a<add>((*seq.begin()).rest) &&
 425                    ex_to<numeric>((*seq.begin()).coeff).is_equal(*_num1_p)) {
 426                 // *(+(x,y,...);c) -> +(*(x,c),*(y,c),...) (c numeric(), no powers of +())
 427                 const add & addref = ex_to<add>((*seq.begin()).rest);
 428                 std::auto_ptr<epvector> distrseq(new epvector);
 429                 distrseq->reserve(addref.seq.size());
 430                 epvector::const_iterator i = addref.seq.begin(), end = addref.seq.end();
 431                 while (i != end) {
 432                         distrseq->push_back(addref.combine_pair_with_coeff_to_pair(*i, overall_coeff));
 433                         ++i;
 434                 }
 435                 return (new add(distrseq,
 436                                 ex_to<numeric>(addref.overall_coeff).
 437                                 mul_dyn(ex_to<numeric>(overall_coeff))))
 438                       ->setflag(status_flags::dynallocated | status_flags::evaluated);
 439         }
 440         return this->hold();
 441 }
 442
 443 ex mul::evalf(int level) const
 444 {
 445         if (level==1)
 446                 return mul(seq,overall_coeff);
 447
 448         if (level==-max_recursion_level)
 449                 throw(std::runtime_error("max recursion level reached"));
 450
 451         std::auto_ptr<epvector> s(new epvector);
 452         s->reserve(seq.size());
 453
 454         --level;
 455         epvector::const_iterator i = seq.begin(), end = seq.end();
 456         while (i != end) {
 457                 s->push_back(combine_ex_with_coeff_to_pair(i->rest.evalf(level),
 458                                                            i->coeff));
 459                 ++i;
 460         }
 461         return mul(s, overall_coeff.evalf(level));
 462 }
 463
 464 ex mul::evalm() const
 465 {
 466         // numeric*matrix
 467         if (seq.size() == 1 && seq[0].coeff.is_equal(_ex1)
 468          && is_a<matrix>(seq[0].rest))
 469                 return ex_to<matrix>(seq[0].rest).mul(ex_to<numeric>(overall_coeff));
 470
 471         // Evaluate children first, look whether there are any matrices at all
 472         // (there can be either no matrices or one matrix; if there were more
 473         // than one matrix, it would be a non-commutative product)
 474         std::auto_ptr<epvector> s(new epvector);
 475         s->reserve(seq.size());
 476
 477         bool have_matrix = false;
 478         epvector::iterator the_matrix;
 479
 480         epvector::const_iterator i = seq.begin(), end = seq.end();
 481         while (i != end) {
 482                 const ex &m = recombine_pair_to_ex(*i).evalm();
 483                 s->push_back(split_ex_to_pair(m));
 484                 if (is_a<matrix>(m)) {
 485                         have_matrix = true;
 486                         the_matrix = s->end() - 1;
 487                 }
 488                 ++i;
 489         }
 490
 491         if (have_matrix) {
 492
 493                 // The product contained a matrix. We will multiply all other factors
 494                 // into that matrix.
 495                 matrix m = ex_to<matrix>(the_matrix->rest);
 496                 s->erase(the_matrix);
 497                 ex scalar = (new mul(s, overall_coeff))->setflag(status_flags::dynallocated);
 498                 return m.mul_scalar(scalar);
 499
 500         } else
 501                 return (new mul(s, overall_coeff))->setflag(status_flags::dynallocated);
 502 }
 503
 504 ex mul::eval_ncmul(const exvector & v) const
 505 {
 506         if (seq.empty())
 507                 return inherited::eval_ncmul(v);
 508
 509         // Find first noncommutative element and call its eval_ncmul()
 510         epvector::const_iterator i = seq.begin(), end = seq.end();
 511         while (i != end) {
 512                 if (i->rest.return_type() == return_types::noncommutative)
 513                         return i->rest.eval_ncmul(v);
 514                 ++i;
 515         }
 516         return inherited::eval_ncmul(v);
 517 }
 518
 519 bool tryfactsubs(const ex & origfactor, const ex & patternfactor, int & nummatches, lst & repls)
 520 {
 521         ex origbase;
 522         int origexponent;
 523         int origexpsign;
 524
 525         if (is_exactly_a<power>(origfactor) && origfactor.op(1).info(info_flags::integer)) {
 526                 origbase = origfactor.op(0);
 527                 int expon = ex_to<numeric>(origfactor.op(1)).to_int();
 528                 origexponent = expon > 0 ? expon : -expon;
 529                 origexpsign = expon > 0 ? 1 : -1;
 530         } else {
 531                 origbase = origfactor;
 532                 origexponent = 1;
 533                 origexpsign = 1;
 534         }
 535
 536         ex patternbase;
 537         int patternexponent;
 538         int patternexpsign;
 539
 540         if (is_exactly_a<power>(patternfactor) && patternfactor.op(1).info(info_flags::integer)) {
 541                 patternbase = patternfactor.op(0);
 542                 int expon = ex_to<numeric>(patternfactor.op(1)).to_int();
 543                 patternexponent = expon > 0 ? expon : -expon;
 544                 patternexpsign = expon > 0 ? 1 : -1;
 545         } else {
 546                 patternbase = patternfactor;
 547                 patternexponent = 1;
 548                 patternexpsign = 1;
 549         }
 550
 551         lst saverepls = repls;
 552         if (origexponent < patternexponent || origexpsign != patternexpsign || !origbase.match(patternbase,saverepls))
 553                 return false;
 554         repls = saverepls;
 555
 556         int newnummatches = origexponent / patternexponent;
 557         if (newnummatches < nummatches)
 558                 nummatches = newnummatches;
 559         return true;
 560 }
 561
 562 ex mul::algebraic_subs_mul(const exmap & m, unsigned options) const
 563 {
 564         std::vector<bool> subsed(seq.size(), false);
 565         exvector subsresult(seq.size());
 566
 567         for (exmap::const_iterator it = m.begin(); it != m.end(); ++it) {
 568
 569                 if (is_exactly_a<mul>(it->first)) {
 570
 571                         int nummatches = std::numeric_limits<int>::max();
 572                         std::vector<bool> currsubsed(seq.size(), false);
 573                         bool succeed = true;
 574                         lst repls;
 575
 576                         for (size_t j=0; j<it->first.nops(); j++) {
 577                                 bool found=false;
 578                                 for (size_t k=0; k<nops(); k++) {
 579                                         if (currsubsed[k] || subsed[k])
 580                                                 continue;
 581                                         if (tryfactsubs(op(k), it->first.op(j), nummatches, repls)) {
 582                                                 currsubsed[k] = true;
 583                                                 found = true;
 584                                                 break;
 585                                         }
 586                                 }
 587                                 if (!found) {
 588                                         succeed = false;
 589                                         break;
 590                                 }
 591                         }
 592                         if (!succeed)
 593                                 continue;
 594
 595                         bool foundfirstsubsedfactor = false;
 596                         for (size_t j=0; j<subsed.size(); j++) {
 597                                 if (currsubsed[j]) {
 598                                         if (foundfirstsubsedfactor)
 599                                                 subsresult[j] = op(j);
 600                                         else {
 601                                                 foundfirstsubsedfactor = true;
 602                                                 subsresult[j] = op(j) * power(it->second.subs(ex(repls), subs_options::no_pattern) / it->first.subs(ex(repls), subs_options::no_pattern), nummatches);
 603                                         }
 604                                         subsed[j] = true;
 605                                 }
 606                         }
 607
 608                 } else {
 609
 610                         int nummatches = std::numeric_limits<int>::max();
 611                         lst repls;
 612
 613                         for (size_t j=0; j<this->nops(); j++) {
 614                                 if (!subsed[j] && tryfactsubs(op(j), it->first, nummatches, repls)) {
 615                                         subsed[j] = true;
 616                                         subsresult[j] = op(j) * power(it->second.subs(ex(repls), subs_options::no_pattern) / it->first.subs(ex(repls), subs_options::no_pattern), nummatches);
 617                                 }
 618                         }
 619                 }
 620         }
 621
 622         bool subsfound = false;
 623         for (size_t i=0; i<subsed.size(); i++) {
 624                 if (subsed[i]) {
 625                         subsfound = true;
 626                         break;
 627                 }
 628         }
 629         if (!subsfound)
 630                 return subs_one_level(m, options | subs_options::algebraic);
 631
 632         exvector ev; ev.reserve(nops());
 633         for (size_t i=0; i<nops(); i++) {
 634                 if (subsed[i])
 635                         ev.push_back(subsresult[i]);
 636                 else
 637                         ev.push_back(op(i));
 638         }
 639
 640         return (new mul(ev))->setflag(status_flags::dynallocated);
 641 }
 642
 643 // protected
 644
 645 /** Implementation of ex::diff() for a product.  It applies the product rule.
 646  *  @see ex::diff */
 647 ex mul::derivative(const symbol & s) const
 648 {
 649         size_t num = seq.size();
 650         exvector addseq;
 651         addseq.reserve(num);
 652
 653         // D(a*b*c) = D(a)*b*c + a*D(b)*c + a*b*D(c)
 654         epvector mulseq = seq;
 655         epvector::const_iterator i = seq.begin(), end = seq.end();
 656         epvector::iterator i2 = mulseq.begin();
 657         while (i != end) {
 658                 expair ep = split_ex_to_pair(power(i->rest, i->coeff - _ex1) *
 659                                              i->rest.diff(s));
 660                 ep.swap(*i2);
 661                 addseq.push_back((new mul(mulseq, overall_coeff * i->coeff))->setflag(status_flags::dynallocated));
 662                 ep.swap(*i2);
 663                 ++i; ++i2;
 664         }
 665         return (new add(addseq))->setflag(status_flags::dynallocated);
 666 }
 667
 668 int mul::compare_same_type(const basic & other) const
 669 {
 670         return inherited::compare_same_type(other);
 671 }
 672
 673 unsigned mul::return_type() const
 674 {
 675         if (seq.empty()) {
 676                 // mul without factors: should not happen, but commutates
 677                 return return_types::commutative;
 678         }
 679
 680         bool all_commutative = true;
 681         epvector::const_iterator noncommutative_element; // point to first found nc element
 682
 683         epvector::const_iterator i = seq.begin(), end = seq.end();
 684         while (i != end) {
 685                 unsigned rt = i->rest.return_type();
 686                 if (rt == return_types::noncommutative_composite)
 687                         return rt; // one ncc -> mul also ncc
 688                 if ((rt == return_types::noncommutative) && (all_commutative)) {
 689                         // first nc element found, remember position
 690                         noncommutative_element = i;
 691                         all_commutative = false;
 692                 }
 693                 if ((rt == return_types::noncommutative) && (!all_commutative)) {
 694                         // another nc element found, compare type_infos
 695                         if (noncommutative_element->rest.return_type_tinfo() != i->rest.return_type_tinfo()) {
 696                                 // diffent types -> mul is ncc
 697                                 return return_types::noncommutative_composite;
 698                         }
 699                 }
 700                 ++i;
 701         }
 702         // all factors checked
 703         return all_commutative ? return_types::commutative : return_types::noncommutative;
 704 }
 705
 706 unsigned mul::return_type_tinfo() const
 707 {
 708         if (seq.empty())
 709                 return tinfo_key;  // mul without factors: should not happen
 710
 711         // return type_info of first noncommutative element
 712         epvector::const_iterator i = seq.begin(), end = seq.end();
 713         while (i != end) {
 714                 if (i->rest.return_type() == return_types::noncommutative)
 715                         return i->rest.return_type_tinfo();
 716                 ++i;
 717         }
 718         // no noncommutative element found, should not happen
 719         return tinfo_key;
 720 }
 721
 722 ex mul::thisexpairseq(const epvector & v, const ex & oc) const
 723 {
 724         return (new mul(v, oc))->setflag(status_flags::dynallocated);
 725 }
 726
 727 ex mul::thisexpairseq(std::auto_ptr<epvector> vp, const ex & oc) const
 728 {
 729         return (new mul(vp, oc))->setflag(status_flags::dynallocated);
 730 }
 731
 732 expair mul::split_ex_to_pair(const ex & e) const
 733 {
 734         if (is_exactly_a<power>(e)) {
 735                 const power & powerref = ex_to<power>(e);
 736                 if (is_exactly_a<numeric>(powerref.exponent))
 737                         return expair(powerref.basis,powerref.exponent);
 738         }
 739         return expair(e,_ex1);
 740 }
 741
 742 expair mul::combine_ex_with_coeff_to_pair(const ex & e,
 743                                           const ex & c) const
 744 {
 745         // to avoid duplication of power simplification rules,
 746         // we create a temporary power object
 747         // otherwise it would be hard to correctly evaluate
 748         // expression like (4^(1/3))^(3/2)
 749         if (c.is_equal(_ex1))
 750                 return split_ex_to_pair(e);
 751
 752         return split_ex_to_pair(power(e,c));
 753 }
 754
 755 expair mul::combine_pair_with_coeff_to_pair(const expair & p,
 756                                             const ex & c) const
 757 {
 758         // to avoid duplication of power simplification rules,
 759         // we create a temporary power object
 760         // otherwise it would be hard to correctly evaluate
 761         // expression like (4^(1/3))^(3/2)
 762         if (c.is_equal(_ex1))
 763                 return p;
 764
 765         return split_ex_to_pair(power(recombine_pair_to_ex(p),c));
 766 }
 767
 768 ex mul::recombine_pair_to_ex(const expair & p) const
 769 {
 770         if (ex_to<numeric>(p.coeff).is_equal(*_num1_p))
 771                 return p.rest;
 772         else
 773                 return (new power(p.rest,p.coeff))->setflag(status_flags::dynallocated);
 774 }
 775
 776 bool mul::expair_needs_further_processing(epp it)
 777 {
 778         if (is_exactly_a<mul>(it->rest) &&
 779                 ex_to<numeric>(it->coeff).is_integer()) {
 780                 // combined pair is product with integer power -> expand it
 781                 *it = split_ex_to_pair(recombine_pair_to_ex(*it));
 782                 return true;
 783         }
 784         if (is_exactly_a<numeric>(it->rest)) {
 785                 expair ep = split_ex_to_pair(recombine_pair_to_ex(*it));
 786                 if (!ep.is_equal(*it)) {
 787                         // combined pair is a numeric power which can be simplified
 788                         *it = ep;
 789                         return true;
 790                 }
 791                 if (it->coeff.is_equal(_ex1)) {
 792                         // combined pair has coeff 1 and must be moved to the end
 793                         return true;
 794                 }
 795         }
 796         return false;
 797 }
 798
 799 ex mul::default_overall_coeff() const
 800 {
 801         return _ex1;
 802 }
 803
 804 void mul::combine_overall_coeff(const ex & c)
 805 {
 806         GINAC_ASSERT(is_exactly_a<numeric>(overall_coeff));
 807         GINAC_ASSERT(is_exactly_a<numeric>(c));
 808         overall_coeff = ex_to<numeric>(overall_coeff).mul_dyn(ex_to<numeric>(c));
 809 }
 810
 811 void mul::combine_overall_coeff(const ex & c1, const ex & c2)
 812 {
 813         GINAC_ASSERT(is_exactly_a<numeric>(overall_coeff));
 814         GINAC_ASSERT(is_exactly_a<numeric>(c1));
 815         GINAC_ASSERT(is_exactly_a<numeric>(c2));
 816         overall_coeff = ex_to<numeric>(overall_coeff).mul_dyn(ex_to<numeric>(c1).power(ex_to<numeric>(c2)));
 817 }
 818
 819 bool mul::can_make_flat(const expair & p) const
 820 {
 821         GINAC_ASSERT(is_exactly_a<numeric>(p.coeff));
 822         // this assertion will probably fail somewhere
 823         // it would require a more careful make_flat, obeying the power laws
 824         // probably should return true only if p.coeff is integer
 825         return ex_to<numeric>(p.coeff).is_equal(*_num1_p);
 826 }
 827
 828 bool mul::can_be_further_expanded(const ex & e)
 829 {
 830         if (is_exactly_a<mul>(e)) {
 831                 for (epvector::const_iterator cit = ex_to<mul>(e).seq.begin(); cit != ex_to<mul>(e).seq.end(); ++cit) {
 832                         if (is_exactly_a<add>(cit->rest) && cit->coeff.info(info_flags::posint))
 833                                 return true;
 834                 }
 835         } else if (is_exactly_a<power>(e)) {
 836                 if (is_exactly_a<add>(e.op(0)) && e.op(1).info(info_flags::posint))
 837                         return true;
 838         }
 839         return false;
 840 }
 841
 842 ex mul::expand(unsigned options) const
 843 {
 844         // First, expand the children
 845         std::auto_ptr<epvector> expanded_seqp = expandchildren(options);
 846         const epvector & expanded_seq = (expanded_seqp.get() ? *expanded_seqp : seq);
 847
 848         // Now, look for all the factors that are sums and multiply each one out
 849         // with the next one that is found while collecting the factors which are
 850         // not sums
 851         ex last_expanded = _ex1;
 852
 853         epvector non_adds;
 854         non_adds.reserve(expanded_seq.size());
 855
 856         for (epvector::const_iterator cit = expanded_seq.begin(); cit != expanded_seq.end(); ++cit) {
 857                 if (is_exactly_a<add>(cit->rest) &&
 858                         (cit->coeff.is_equal(_ex1))) {
 859                         if (is_exactly_a<add>(last_expanded)) {
 860
 861                                 // Expand a product of two sums, aggressive version.
 862                                 // Caring for the overall coefficients in separate loops can
 863                                 // sometimes give a performance gain of up to 15%!
 864
 865                                 const int sizedifference = ex_to<add>(last_expanded).seq.size()-ex_to<add>(cit->rest).seq.size();
 866                                 // add2 is for the inner loop and should be the bigger of the two sums
 867                                 // in the presence of asymptotically good sorting:
 868                                 const add& add1 = (sizedifference<0 ? ex_to<add>(last_expanded) : ex_to<add>(cit->rest));
 869                                 const add& add2 = (sizedifference<0 ? ex_to<add>(cit->rest) : ex_to<add>(last_expanded));
 870                                 const epvector::const_iterator add1begin = add1.seq.begin();
 871                                 const epvector::const_iterator add1end   = add1.seq.end();
 872                                 const epvector::const_iterator add2begin = add2.seq.begin();
 873                                 const epvector::const_iterator add2end   = add2.seq.end();
 874                                 epvector distrseq;
 875                                 distrseq.reserve(add1.seq.size()+add2.seq.size());
 876
 877                                 // Multiply add2 with the overall coefficient of add1 and append it to distrseq:
 878                                 if (!add1.overall_coeff.is_zero()) {
 879                                         if (add1.overall_coeff.is_equal(_ex1))
 880                                                 distrseq.insert(distrseq.end(),add2begin,add2end);
 881                                         else
 882                                                 for (epvector::const_iterator i=add2begin; i!=add2end; ++i)
 883                                                         distrseq.push_back(expair(i->rest, ex_to<numeric>(i->coeff).mul_dyn(ex_to<numeric>(add1.overall_coeff))));
 884                                 }
 885
 886                                 // Multiply add1 with the overall coefficient of add2 and append it to distrseq:
 887                                 if (!add2.overall_coeff.is_zero()) {
 888                                         if (add2.overall_coeff.is_equal(_ex1))
 889                                                 distrseq.insert(distrseq.end(),add1begin,add1end);
 890                                         else
 891                                                 for (epvector::const_iterator i=add1begin; i!=add1end; ++i)
 892                                                         distrseq.push_back(expair(i->rest, ex_to<numeric>(i->coeff).mul_dyn(ex_to<numeric>(add2.overall_coeff))));
 893                                 }
 894
 895                                 // Compute the new overall coefficient and put it together:
 896                                 ex tmp_accu = (new add(distrseq, add1.overall_coeff*add2.overall_coeff))->setflag(status_flags::dynallocated);
 897
 898                                 // Multiply explicitly all non-numeric terms of add1 and add2:
 899                                 for (epvector::const_iterator i1=add1begin; i1!=add1end; ++i1) {
 900                                         // We really have to combine terms here in order to compactify
 901                                         // the result.  Otherwise it would become waayy tooo bigg.
 902                                         numeric oc;
 903                                         distrseq.clear();
 904                                         for (epvector::const_iterator i2=add2begin; i2!=add2end; ++i2) {
 905                                                 // Don't push_back expairs which might have a rest that evaluates to a numeric,
 906                                                 // since that would violate an invariant of expairseq:
 907                                                 const ex rest = (new mul(i1->rest, rename_dummy_indices_uniquely(i1->rest, i2->rest)))->setflag(status_flags::dynallocated);
 908                                                 if (is_exactly_a<numeric>(rest)) {
 909                                                         oc += ex_to<numeric>(rest).mul(ex_to<numeric>(i1->coeff).mul(ex_to<numeric>(i2->coeff)));
 910                                                 } else {
 911                                                         distrseq.push_back(expair(rest, ex_to<numeric>(i1->coeff).mul_dyn(ex_to<numeric>(i2->coeff))));
 912                                                 }
 913                                         }
 914                                         tmp_accu += (new add(distrseq, oc))->setflag(status_flags::dynallocated);
 915                                 }
 916                                 last_expanded = tmp_accu;
 917
 918                         } else {
 919                                 if (!last_expanded.is_equal(_ex1))
 920                                         non_adds.push_back(split_ex_to_pair(last_expanded));
 921                                 last_expanded = cit->rest;
 922                         }
 923
 924                 } else {
 925                         non_adds.push_back(*cit);
 926                 }
 927         }
 928
 929         // Now the only remaining thing to do is to multiply the factors which
 930         // were not sums into the "last_expanded" sum
 931         if (is_exactly_a<add>(last_expanded)) {
 932                 size_t n = last_expanded.nops();
 933                 exvector distrseq;
 934                 distrseq.reserve(n);
 935
 936                 for (size_t i=0; i<n; ++i) {
 937                         epvector factors = non_adds;
 938                         factors.push_back(split_ex_to_pair(rename_dummy_indices_uniquely(mul(non_adds), last_expanded.op(i))));
 939                         ex term = (new mul(factors, overall_coeff))->setflag(status_flags::dynallocated);
 940                         if (can_be_further_expanded(term)) {
 941                                 distrseq.push_back(term.expand());
 942                         } else {
 943                                 if (options == 0)
 944                                         ex_to<basic>(term).setflag(status_flags::expanded);
 945                                 distrseq.push_back(term);
 946                         }
 947                 }
 948
 949                 return ((new add(distrseq))->
 950                         setflag(status_flags::dynallocated | (options == 0 ? status_flags::expanded : 0)));
 951         }
 952
 953         non_adds.push_back(split_ex_to_pair(last_expanded));
 954         ex result = (new mul(non_adds, overall_coeff))->setflag(status_flags::dynallocated);
 955         if (can_be_further_expanded(result)) {
 956                 return result.expand();
 957         } else {
 958                 if (options == 0)
 959                         ex_to<basic>(result).setflag(status_flags::expanded);
 960                 return result;
 961         }
 962 }
 963
 964
 965 //////////
 966 // new virtual functions which can be overridden by derived classes
 967 //////////
 968
 969 // none
 970
 971 //////////
 972 // non-virtual functions in this class
 973 //////////
 974
 975
 976 /** Member-wise expand the expairs representing this sequence.  This must be
 977  *  overridden from expairseq::expandchildren() and done iteratively in order
 978  *  to allow for early cancallations and thus safe memory.
 979  *
 980  *  @see mul::expand()
 981  *  @return pointer to epvector containing expanded representation or zero
 982  *  pointer, if sequence is unchanged. */
 983 std::auto_ptr<epvector> mul::expandchildren(unsigned options) const
 984 {
 985         const epvector::const_iterator last = seq.end();
 986         epvector::const_iterator cit = seq.begin();
 987         while (cit!=last) {
 988                 const ex & factor = recombine_pair_to_ex(*cit);
 989                 const ex & expanded_factor = factor.expand(options);
 990                 if (!are_ex_trivially_equal(factor,expanded_factor)) {
 991
 992                         // something changed, copy seq, eval and return it
 993                         std::auto_ptr<epvector> s(new epvector);
 994                         s->reserve(seq.size());
 995
 996                         // copy parts of seq which are known not to have changed
 997                         epvector::const_iterator cit2 = seq.begin();
 998                         while (cit2!=cit) {
 999                                 s->push_back(*cit2);
1000                                 ++cit2;
1001                         }
1002
1003                         // copy first changed element
1004                         s->push_back(split_ex_to_pair(expanded_factor));
1005                         ++cit2;
1006
1007                         // copy rest
1008                         while (cit2!=last) {
1009                                 s->push_back(split_ex_to_pair(recombine_pair_to_ex(*cit2).expand(options)));
1010                                 ++cit2;
1011                         }
1012                         return s;
1013                 }
1014                 ++cit;
1015         }
1016
1017         return std::auto_ptr<epvector>(0); // nothing has changed
1018 }
1019
1020 } // namespace GiNaC