primpart_content: correctly handle monomials.

[ginac.git] / ginac / polynomial / collect_vargs.cpp

diff --git a/ginac/polynomial/collect_vargs.cpp b/ginac/polynomial/collect_vargs.cpp
index 89c3b8bec49321e8adffc70df2db2e8d94f4be9a..259326873bf1da4fd6866a8d2267ec0a13665264 100644 (file)
--- a/ginac/polynomial/collect_vargs.cpp
+++ b/ginac/polynomial/collect_vargs.cpp
@@ -148,8 +148,14 @@ ex_collect_to_ex(const ex_collect_t& ec, const GiNaC::exvector& vars)
                exvector tv;
                tv.reserve(vars.size() + 1);
                for (std::size_t j = 0; j < vars.size(); ++j) {
-                       if (ec[i].first[j] != 0)
-                               tv.push_back(power(vars[j], ec[i].first[j]));
+                       const exp_vector_t& exp_vector(ec[i].first);
+
+                       bug_on(exp_vector.size() != vars.size(),
+                               "expected " << vars.size() << " variables, "
+                               "expression has " << exp_vector.size() << " instead");
+
+                       if (exp_vector[j] != 0)
+                               tv.push_back(power(vars[j], exp_vector[j]));
                }
                tv.push_back(ec[i].second);
                ex tmp = (new mul(tv))->setflag(status_flags::dynallocated);