From b23a2dfdcd478b00a11c6c2184fbe197a3ac5bfb Mon Sep 17 00:00:00 2001
From: Alexei Sheplyakov <Alexei.Sheplyakov@gmail.com>
Date: Sun, 28 Jul 2013 18:43:06 +0300
Subject: [PATCH] [bugfix] factor_univariate(): handle polinomials over
 rationals (no segfaults any more).

---
 check/CMakeLists.txt            |  1 +
 check/Makefile.am               |  4 ++++
 check/factor_univariate_bug.cpp | 21 +++++++++++++++++++++
 ginac/factor.cpp                | 12 +++++++++++-
 4 files changed, 37 insertions(+), 1 deletion(-)
 create mode 100644 check/factor_univariate_bug.cpp

diff --git a/check/CMakeLists.txt b/check/CMakeLists.txt
index 0243617c..0445a4a1 100644
--- a/check/CMakeLists.txt
+++ b/check/CMakeLists.txt
@@ -33,6 +33,7 @@ set(ginac_tests
 	exam_mod_gcd
 	exam_cra
 	bugme_chinrem_gcd
+	factor_univariate_bug
 	pgcd_relatively_prime_bug
 	pgcd_infinite_loop)
 
diff --git a/check/Makefile.am b/check/Makefile.am
index 7aaed071..e17e5a59 100644
--- a/check/Makefile.am
+++ b/check/Makefile.am
@@ -30,6 +30,7 @@ EXAMS = exam_paranoia \
 	exam_misc \
 	exam_mod_gcd \
 	bugme_chinrem_gcd \
+	factor_univariate_bug \
 	pgcd_relatively_prime_bug \
 	pgcd_infinite_loop \
 	exam_cra
@@ -257,6 +258,9 @@ time_parser_LDADD = ../ginac/libginac.la
 bugme_chinrem_gcd_SOURCES = bugme_chinrem_gcd.cpp
 bugme_chinrem_gcd_LDADD = ../ginac/libginac.la
 
+factor_univariate_bug_SOURCES = factor_univariate_bug.cpp
+factor_univariate_bug_LDADD = ../ginac/libginac.la
+
 pgcd_relatively_prime_bug_SOURCES = pgcd_relatively_prime_bug.cpp
 pgcd_relatively_prime_bug_LDADD = ../ginac/libginac.la
 
diff --git a/check/factor_univariate_bug.cpp b/check/factor_univariate_bug.cpp
new file mode 100644
index 00000000..80a7ce4c
--- /dev/null
+++ b/check/factor_univariate_bug.cpp
@@ -0,0 +1,21 @@
+/**
+ * @file factor_upoly_q_bug.cpp Check for a bug in factor_univariate().
+ *
+ * factor_univariate() didn't check if the argument is an integer polynomial,
+ * the result was a segfault.
+ */
+#include "ginac.h"
+#include <iostream>
+using namespace GiNaC;
+using namespace std;
+
+int main(int argc, char** argv)
+{
+	cout << "checking if factor() handles rational polynomials. ";
+	parser p;
+	ex e = p("174247781*x^2-1989199947807987/200000000000000*x");
+	ex ef = factor(e);
+	ex diff = (e - ef).expand();
+	cout << "yes" << endl;
+	return 0;
+}
diff --git a/ginac/factor.cpp b/ginac/factor.cpp
index 945b25e6..24f828cb 100644
--- 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;
-- 
2.49.0