More evaluation rules: abs(x^n) => abs(x)^n (x > 0, n is real).

[ginac.git] / ginac / factor.cpp

diff --git a/ginac/factor.cpp b/ginac/factor.cpp
index c82e74405658de2800cda0f8156f18df74163f81..24f828cb793e9ad9d11e5104a4904d64345cd993 100644 (file)
--- a/ginac/factor.cpp
+++ b/ginac/factor.cpp
@@ -33,7 +33,7 @@
  */
 
 /*
- *  GiNaC Copyright (C) 1999-2009 Johannes Gutenberg University Mainz, Germany
+ *  GiNaC Copyright (C) 1999-2011 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
@@ -737,7 +737,6 @@ public:
        }
        bool is_col_zero(size_t col) const
        {
-               mvec::const_iterator i = m.begin() + col;
                for ( size_t rr=0; rr<r; ++rr ) {
                        std::size_t i = col + rr*c;
                        if ( !zerop(m[i]) ) {
@@ -1510,7 +1509,17 @@ static ex factor_univariate(const ex& poly, const ex& x, unsigned int& prime)
        cl_modint_ring R;
        unsigned int trials = 0;
        unsigned int minfactors = 0;
-       cl_I lc = lcoeff(prim) * the<cl_I>(ex_to<numeric>(cont).to_cl_N());
+
+       const numeric& cont_n = ex_to<numeric>(cont);
+       cl_I i_cont;
+       if (cont_n.is_integer()) {
+               i_cont = the<cl_I>(cont_n.to_cl_N());
+       } else {
+               // poly \in Q[x] => poly = q ipoly, ipoly \in Z[x], q \in Q
+               // factor(poly) \equiv q factor(ipoly)
+               i_cont = cl_I(1);
+       }
+       cl_I lc = lcoeff(prim)*i_cont;
        upvec factors;
        while ( trials < 2 ) {
                umodpoly modpoly;