Added `degree_vector' utility function.

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

diff --git a/ginac/polynomial/collect_vargs.cpp b/ginac/polynomial/collect_vargs.cpp
index 6dc26f6d6bfba5cf55945eadc34f19af27f1013c..c4368fb2a5d2c1849f1b8d377ba5fddd3b8ecd7a 100644 (file)
--- a/ginac/polynomial/collect_vargs.cpp
+++ b/ginac/polynomial/collect_vargs.cpp
@@ -3,7 +3,7 @@
  *  Utility functions. */
 
 /*
  *  Utility functions. */
 
 /*

- *  GiNaC Copyright (C) 1999-2009 Johannes Gutenberg University Mainz, Germany
+ *  GiNaC Copyright (C) 1999-2010 Johannes Gutenberg University Mainz, Germany

  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by


@@ -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) {
                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);
                }
                tv.push_back(ec[i].second);
                ex tmp = (new mul(tv))->setflag(status_flags::dynallocated);


@@ -171,6 +177,18 @@ ex lcoeff_wrt(ex e, const exvector& x)
        return ec.rbegin()->second;
 }
 
        return ec.rbegin()->second;
 }
 

+exp_vector_t degree_vector(ex e, const exvector& vars)
+{
+       e = e.expand();
+       exp_vector_t dvec(vars.size());
+       for (std::size_t i = vars.size(); i-- != 0; ) {
+               const int deg_i = e.degree(vars[i]);
+               e = e.coeff(vars[i], deg_i);
+               dvec[i] = deg_i;
+       }
+       return dvec;
+}
+

 cln::cl_I integer_lcoeff(const ex& e, const exvector& vars)
 {
        ex_collect_t ec;
 cln::cl_I integer_lcoeff(const ex& e, const exvector& vars)
 {
        ex_collect_t ec;