[BUGFIX] Speed up some cases of polynomial factorization.

[ginac.git] / ginac / factor.cpp

diff --git a/ginac/factor.cpp b/ginac/factor.cpp
index c978bab5574308015ec0af5e9b63feb267b1e847..cfb9e29d9000b81410b4dba4858cdd62325ba1ac 100644 (file)
--- a/ginac/factor.cpp
+++ b/ginac/factor.cpp
@@ -66,7 +66,6 @@
 #include "add.h"
 
 #include <algorithm>
-#include <cmath>
 #include <limits>
 #include <list>
 #include <vector>
@@ -1874,7 +1873,8 @@ static vector<ex> multivar_diophant(const vector<ex>& a_, const ex& x, const ex&
 {
        vector<ex> a = a_;
 
-       const cl_modint_ring R = find_modint_ring(expt_pos(cl_I(p),k));
+       const cl_I modulus = expt_pos(cl_I(p),k);
+       const cl_modint_ring R = find_modint_ring(modulus);
        const size_t r = a.size();
        const size_t nu = I.size() + 1;
 
@@ -1947,10 +1947,7 @@ static vector<ex> multivar_diophant(const vector<ex>& a_, const ex& x, const ex&
                        cl_I cm = the<cl_I>(ex_to<numeric>(z.lcoeff(x)).to_cl_N());
                        upvec delta_s = univar_diophant(amod, x, m, p, k);
                        cl_MI modcm;
-                       cl_I poscm = cm;
-                       while ( poscm < 0 ) {
-                               poscm = poscm + expt_pos(cl_I(p),k);
-                       }
+                       cl_I poscm = plusp(cm) ? cm : mod(cm, modulus);
                        modcm = cl_MI(R, poscm);
                        for ( size_t j=0; j<delta_s.size(); ++j ) {
                                delta_s[j] = delta_s[j] * modcm;