From: Christian Bauer Date: Mon, 25 Jun 2001 22:04:03 +0000 (+0000) Subject: some more comments and cleanups to mul::expand() and ncmul::expand() X-Git-Tag: release_0-9-1~17 X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?p=ginac.git;a=commitdiff_plain;h=b6e3c62f240698c7e9ed464c57bb6d92741765ba;ds=sidebyside some more comments and cleanups to mul::expand() and ncmul::expand() --- diff --git a/ginac/add.cpp b/ginac/add.cpp index 5a4c805d..7764d368 100644 --- a/ginac/add.cpp +++ b/ginac/add.cpp @@ -511,9 +511,6 @@ ex add::recombine_pair_to_ex(const expair & p) const ex add::expand(unsigned options) const { - if (options == 0 && (flags & status_flags::expanded)) - return *this; - epvector *vp = expandchildren(options); if (vp == NULL) { // the terms have not changed, so it is safe to declare this expanded diff --git a/ginac/expairseq.cpp b/ginac/expairseq.cpp index a18927c2..f49fefcf 100644 --- a/ginac/expairseq.cpp +++ b/ginac/expairseq.cpp @@ -311,7 +311,10 @@ ex expairseq::map(map_function & f) const ++cit; } - return thisexpairseq(v, f(overall_coeff)); + if (overall_coeff.is_equal(default_overall_coeff())) + return thisexpairseq(v, default_overall_coeff()); + else + return thisexpairseq(v, f(overall_coeff)); } ex expairseq::eval(int level) const diff --git a/ginac/mul.cpp b/ginac/mul.cpp index 2cb358ef..92e21b3e 100644 --- a/ginac/mul.cpp +++ b/ginac/mul.cpp @@ -668,42 +668,39 @@ bool mul::can_make_flat(const expair & p) const ex mul::expand(unsigned options) const { - if (options == 0 && (flags & status_flags::expanded)) - return *this; - - exvector sub_expanded_seq; - + // First, expand the children epvector * expanded_seqp = expandchildren(options); - - const epvector & expanded_seq = expanded_seqp==0 ? seq : *expanded_seqp; - + const epvector & expanded_seq = (expanded_seqp == NULL) ? seq : *expanded_seqp; + + // Now, look for all the factors that are sums and multiply each one out + // with the next one that is found while collecting the factors which are + // not sums int number_of_adds = 0; + ex last_expanded = _ex1(); epvector non_adds; non_adds.reserve(expanded_seq.size()); - epvector::const_iterator cit = expanded_seq.begin(); - epvector::const_iterator last = expanded_seq.end(); - ex last_expanded = _ex1(); - while (cit!=last) { - if (is_ex_exactly_of_type((*cit).rest,add) && - ((*cit).coeff.is_equal(_ex1()))) { + epvector::const_iterator cit = expanded_seq.begin(), last = expanded_seq.end(); + while (cit != last) { + if (is_ex_exactly_of_type(cit->rest, add) && + (cit->coeff.is_equal(_ex1()))) { ++number_of_adds; - if (is_ex_exactly_of_type(last_expanded,add)) { - // expand adds + if (is_ex_exactly_of_type(last_expanded, add)) { const add & add1 = ex_to(last_expanded); - const add & add2 = ex_to((*cit).rest); + const add & add2 = ex_to(cit->rest); int n1 = add1.nops(); int n2 = add2.nops(); exvector distrseq; distrseq.reserve(n1*n2); for (int i1=0; i1setflag(status_flags::dynallocated | (options == 0 ? status_flags::expanded : 0)); + last_expanded = (new add(distrseq))-> + setflag(status_flags::dynallocated | (options == 0 ? status_flags::expanded : 0)); } else { non_adds.push_back(split_ex_to_pair(last_expanded)); - last_expanded = (*cit).rest; + last_expanded = cit->rest; } } else { non_adds.push_back(*cit); @@ -713,7 +710,9 @@ ex mul::expand(unsigned options) const if (expanded_seqp) delete expanded_seqp; - if (is_ex_exactly_of_type(last_expanded,add)) { + // Now the only remaining thing to do is to multiply the factors which + // were not sums into the "last_expanded" sum + if (is_ex_exactly_of_type(last_expanded, add)) { add const & finaladd = ex_to(last_expanded); exvector distrseq; int n = finaladd.nops(); @@ -721,7 +720,8 @@ ex mul::expand(unsigned options) const for (int i=0; isetflag(status_flags::dynallocated | (options == 0 ? status_flags::expanded : 0))); + distrseq.push_back((new mul(factors, overall_coeff))-> + setflag(status_flags::dynallocated | (options == 0 ? status_flags::expanded : 0))); } return ((new add(distrseq))-> setflag(status_flags::dynallocated | (options == 0 ? status_flags::expanded : 0))); diff --git a/ginac/ncmul.cpp b/ginac/ncmul.cpp index 25ffca31..c4cfe69c 100644 --- a/ginac/ncmul.cpp +++ b/ginac/ncmul.cpp @@ -147,69 +147,69 @@ typedef std::vector intvector; ex ncmul::expand(unsigned options) const { - exvector sub_expanded_seq; - intvector positions_of_adds; - intvector number_of_add_operands; - - exvector expanded_seq=expandchildren(options); - - positions_of_adds.resize(expanded_seq.size()); - number_of_add_operands.resize(expanded_seq.size()); - - int number_of_adds=0; - int number_of_expanded_terms=1; - - unsigned current_position=0; - exvector::const_iterator last=expanded_seq.end(); + // First, expand the children + exvector expanded_seq = expandchildren(options); + + // Now, look for all the factors that are sums and remember their + // position and number of terms. One remark is in order here: we do not + // take into account the overall_coeff of the add objects. This is + // because in GiNaC, all terms of a sum must be of the same type, so + // a non-zero overall_coeff (which can only be numeric) would imply that + // the sum only has commutative terms. But then it would never appear + // as a factor of an ncmul. + intvector positions_of_adds(expanded_seq.size()); + intvector number_of_add_operands(expanded_seq.size()); + + int number_of_adds = 0; + int number_of_expanded_terms = 1; + + unsigned current_position = 0; + exvector::const_iterator last = expanded_seq.end(); for (exvector::const_iterator cit=expanded_seq.begin(); cit!=last; ++cit) { - if (is_ex_exactly_of_type((*cit),add)) { - positions_of_adds[number_of_adds]=current_position; - const add & expanded_addref=ex_to(*cit); - number_of_add_operands[number_of_adds]=expanded_addref.seq.size(); + if (is_ex_exactly_of_type(*cit, add)) { + positions_of_adds[number_of_adds] = current_position; + const add & expanded_addref = ex_to(*cit); + number_of_add_operands[number_of_adds] = expanded_addref.seq.size(); number_of_expanded_terms *= expanded_addref.seq.size(); number_of_adds++; } current_position++; } - if (number_of_adds==0) { - return (new ncmul(expanded_seq,1))->setflag(status_flags::dynallocated || - (options == 0 ? status_flags::expanded : 0)); - } + // If there are no sums, we are done + if (number_of_adds == 0) + return (new ncmul(expanded_seq, true))-> + setflag(status_flags::dynallocated | (options == 0 ? status_flags::expanded : 0)); + // Now, form all possible products of the terms of the sums with the + // remaining factors, and add them together exvector distrseq; distrseq.reserve(number_of_expanded_terms); - intvector k; - k.resize(number_of_adds); - - int l; - for (l=0; l(expanded_seq[positions_of_adds[l]]); - term[positions_of_adds[l]]=addref.recombine_pair_to_ex(addref.seq[k[l]]); + while (true) { + exvector term = expanded_seq; + for (int i=0; i(expanded_seq[positions_of_adds[i]]); + term[positions_of_adds[i]] = addref.recombine_pair_to_ex(addref.seq[k[i]]); } - distrseq.push_back((new ncmul(term,1))->setflag(status_flags::dynallocated | - (options == 0 ? status_flags::expanded : 0))); + distrseq.push_back((new ncmul(term, true))-> + setflag(status_flags::dynallocated | (options == 0 ? status_flags::expanded : 0))); // increment k[] - l=number_of_adds-1; - while ((l>=0)&&((++k[l])>=number_of_add_operands[l])) { - k[l]=0; + int l = number_of_adds-1; + while ((l>=0) && ((++k[l]) >= number_of_add_operands[l])) { + k[l] = 0; l--; } - if (l<0) break; + if (l<0) + break; } - return (new add(distrseq))->setflag(status_flags::dynallocated | - (options == 0 ? status_flags::expanded : 0)); + return (new add(distrseq))-> + setflag(status_flags::dynallocated | (options == 0 ? status_flags::expanded : 0)); } int ncmul::degree(const ex & s) const