[src/mul.c] in mpc_mul_karatsuba, check that a*d and b*c are exact

	    (no underflow nor overflow) otherwise the algorithm might be wrong


git-svn-id: svn://scm.gforge.inria.fr/svn/mpc/trunk@1055 211d60ee-9f03-0410-a15a-8952a2c7a4e4

1 files changed, 4 insertions, 2 deletions

diff --git a/src/mul.c b/src/mul.c
index e49206b..382b06e 100644
--- a/src/mul.c
+++ b/src/mul.c
@@ -418,11 +418,13 @@ mpc_mul_karatsuba (mpc_ptr rop, mpc_srcptr op1, mpc_srcptr op2, mpc_rnd_t rnd)
   mpfr_init2 (w, prec_w = mpfr_get_prec (b) + mpfr_get_prec (c));
   mpfr_init2 (x, 2);
 
-  mpfr_mul (v, a, d, GMP_RNDN); /* exact */
+  inexact = mpfr_mul (v, a, d, GMP_RNDN); /* exact if no underflow/overflow */
+  MPC_ASSERT(inexact == 0);
   if (mul_a == -1)
     mpfr_neg (v, v, GMP_RNDN);
 
-  mpfr_mul (w, b, c, GMP_RNDN); /* exact */
+  inexact = mpfr_mul (w, b, c, GMP_RNDN); /* exact if no underflow/overflow */
+  MPC_ASSERT(inexact == 0);
   if (mul_c == -1)
     mpfr_neg (w, w, GMP_RNDN);