author Alexei Sheplyakov Mon, 25 Aug 2008 12:54:10 +0000 (16:54 +0400) committer Jens Vollinga Wed, 27 Aug 2008 14:22:59 +0000 (16:22 +0200)
GiNaC tries to avoid expanding expressions while computing GCDs and applies
a number of heuristics. Usually this improves performance, but in some cases
it doesn't. Allow user to switch off heuristics.

Part 4:

refactor gcd() a little bit, so subsequent patch(es) won't be so big and ugly.

 ginac/normal.cpp patch | blob | history

index 0cb91001a01ff427bdb353590a3a29210c99c597..0227f4e3fa0c08efd83ec491a9a3ed3189f7cf1f 100644 (file)
@@ -1602,33 +1602,36 @@ ex gcd(const ex &a, const ex &b, ex *ca, ex *cb, bool check_args, unsigned optio
// Try heuristic algorithm first, fall back to PRS if that failed
ex g;
bool found = heur_gcd(g, aex, bex, ca, cb, var);
// Try heuristic algorithm first, fall back to PRS if that failed
ex g;
bool found = heur_gcd(g, aex, bex, ca, cb, var);
-       if (!found) {
-#if STATISTICS
-               heur_gcd_failed++;
-#endif
-               g = sr_gcd(aex, bex, var);
-               if (g.is_equal(_ex1)) {
-                       // Keep cofactors factored if possible
-                       if (ca)
-                               *ca = a;
-                       if (cb)
-                               *cb = b;
-               } else {
-                       if (ca)
-                               divide(aex, g, *ca, false);
-                       if (cb)
-                               divide(bex, g, *cb, false);
-               }
-       } else {
+       if (found) {
+               // heur_gcd have already computed cofactors...
if (g.is_equal(_ex1)) {
if (g.is_equal(_ex1)) {
-                       // Keep cofactors factored if possible
+                       // ... but we want to keep them factored if possible.
if (ca)
*ca = a;
if (cb)
*cb = b;
}
if (ca)
*ca = a;
if (cb)
*cb = b;
}
+               return g;
}
}
+#if STATISTICS
+       else {
+               heur_gcd_failed++;
+       }
+#endif

+       g = sr_gcd(aex, bex, var);
+       if (g.is_equal(_ex1)) {
+               // Keep cofactors factored if possible
+               if (ca)
+                       *ca = a;
+               if (cb)
+                       *cb = b;
+       } else {
+               if (ca)
+                       divide(aex, g, *ca, false);
+               if (cb)
+                       divide(bex, g, *cb, false);
+       }
return g;
}

return g;
}