Transform abs(x)^n => x^n if x is real and n is even.

[ginac.git] / ginac / factor.cpp

diff --git a/ginac/factor.cpp b/ginac/factor.cpp
index 945b25e653a4c56ba59b1ec3abeac50f34a065f8..24f828cb793e9ad9d11e5104a4904d64345cd993 100644 (file)
--- a/ginac/factor.cpp
+++ b/ginac/factor.cpp
@@ -1509,7 +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;