+ return false;
+}
+
+ex mul::expand(unsigned options) const
+{
+ // First, expand the children
+ std::auto_ptr<epvector> expanded_seqp = expandchildren(options);
+ const epvector & expanded_seq = (expanded_seqp.get() ? *expanded_seqp : seq);
+
+ // 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
+ ex last_expanded = _ex1;
+ bool need_reexpand = false;
+
+ epvector non_adds;
+ non_adds.reserve(expanded_seq.size());
+
+ for (epvector::const_iterator cit = expanded_seq.begin(); cit != expanded_seq.end(); ++cit) {
+ if (is_exactly_a<add>(cit->rest) &&
+ (cit->coeff.is_equal(_ex1))) {
+ if (is_exactly_a<add>(last_expanded)) {
+
+ // Expand a product of two sums, aggressive version.
+ // Caring for the overall coefficients in separate loops can
+ // sometimes give a performance gain of up to 15%!
+
+ const int sizedifference = ex_to<add>(last_expanded).seq.size()-ex_to<add>(cit->rest).seq.size();
+ // add2 is for the inner loop and should be the bigger of the two sums
+ // in the presence of asymptotically good sorting:
+ const add& add1 = (sizedifference<0 ? ex_to<add>(last_expanded) : ex_to<add>(cit->rest));
+ const add& add2 = (sizedifference<0 ? ex_to<add>(cit->rest) : ex_to<add>(last_expanded));
+ const epvector::const_iterator add1begin = add1.seq.begin();
+ const epvector::const_iterator add1end = add1.seq.end();
+ const epvector::const_iterator add2begin = add2.seq.begin();
+ const epvector::const_iterator add2end = add2.seq.end();
+ epvector distrseq;
+ distrseq.reserve(add1.seq.size()+add2.seq.size());
+
+ // Multiply add2 with the overall coefficient of add1 and append it to distrseq:
+ if (!add1.overall_coeff.is_zero()) {
+ if (add1.overall_coeff.is_equal(_ex1))
+ distrseq.insert(distrseq.end(),add2begin,add2end);
+ else
+ for (epvector::const_iterator i=add2begin; i!=add2end; ++i)
+ distrseq.push_back(expair(i->rest, ex_to<numeric>(i->coeff).mul_dyn(ex_to<numeric>(add1.overall_coeff))));
+ }
+
+ // Multiply add1 with the overall coefficient of add2 and append it to distrseq:
+ if (!add2.overall_coeff.is_zero()) {
+ if (add2.overall_coeff.is_equal(_ex1))
+ distrseq.insert(distrseq.end(),add1begin,add1end);
+ else
+ for (epvector::const_iterator i=add1begin; i!=add1end; ++i)
+ distrseq.push_back(expair(i->rest, ex_to<numeric>(i->coeff).mul_dyn(ex_to<numeric>(add2.overall_coeff))));
+ }
+
+ // Compute the new overall coefficient and put it together:
+ ex tmp_accu = (new add(distrseq, add1.overall_coeff*add2.overall_coeff))->setflag(status_flags::dynallocated);
+
+ // Multiply explicitly all non-numeric terms of add1 and add2:
+ for (epvector::const_iterator i1=add1begin; i1!=add1end; ++i1) {
+ // We really have to combine terms here in order to compactify
+ // the result. Otherwise it would become waayy tooo bigg.
+ numeric oc;
+ distrseq.clear();
+ for (epvector::const_iterator i2=add2begin; i2!=add2end; ++i2) {
+ // Don't push_back expairs which might have a rest that evaluates to a numeric,
+ // since that would violate an invariant of expairseq:
+ const ex rest = (new mul(i1->rest, i2->rest))->setflag(status_flags::dynallocated);
+ if (is_exactly_a<numeric>(rest))
+ oc += ex_to<numeric>(rest).mul(ex_to<numeric>(i1->coeff).mul(ex_to<numeric>(i2->coeff)));
+ else
+ distrseq.push_back(expair(rest, ex_to<numeric>(i1->coeff).mul_dyn(ex_to<numeric>(i2->coeff))));
+ }
+ tmp_accu += (new add(distrseq, oc))->setflag(status_flags::dynallocated);
+ }
+ last_expanded = tmp_accu;
+
+ } else {
+ if (!last_expanded.is_equal(_ex1))
+ non_adds.push_back(split_ex_to_pair(last_expanded));
+ last_expanded = cit->rest;
+ }
+
+ } else {
+ non_adds.push_back(*cit);