X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?p=ginac.git;a=blobdiff_plain;f=ginac%2Fpolynomial%2Fmod_gcd.cpp;h=82d5f427f397abd6b8e6cce68ac84eb6c03a72e5;hp=8aa84808c1f64a5975086eaa743d78c93f4e4455;hb=d625a28c3def007a9d2d5108141a6f6a4889bf9d;hpb=546bababce8ef2b3c5ed3011cb7e49bd78016844

diff --git a/ginac/polynomial/mod_gcd.cpp b/ginac/polynomial/mod_gcd.cpp
index 8aa84808..82d5f427 100644
--- a/ginac/polynomial/mod_gcd.cpp
+++ b/ginac/polynomial/mod_gcd.cpp
@@ -104,8 +104,18 @@ void mod_gcd(upoly& result, upoly A, upoly B)
 	ring_t q(0);
 	upoly H;
 
-	ring_t p(2);
+	int count = 0;
+	const ring_t p_threshold = ring_t(1) << (8*sizeof(void *));
+	ring_t p = isqrt(std::min(max_coeff(A), max_coeff(B)));
 	while (true) {
+		if (count >= 8) {
+			count = 0;
+			if (p < p_threshold)
+				p <<= 1;
+			else
+				p = p + (p >> 4);
+		} else 
+			++count;
 		find_next_prime(p, g);
 
 		// Map the polynomials onto Z/p[x]