Fixed a sign bug in mpfr_exp (found by Mark J Watkins).

git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/branches/mpfr-2-1-branch@3247 280ebfd0-de03-0410-8827-d642c229c3f4

2 files changed, 6 insertions, 2 deletions

diff --git a/exp.c b/exp.c
index 4682896b8..56fbb9ce9 100644
--- a/exp.c
+++ b/exp.c
@@ -1,6 +1,6 @@
 /* mpfr_exp -- exponential of a floating-point number
 
-Copyright 1999, 2000, 2001, 2002, 2003, 2004 Free Software Foundation.
+Copyright 1999, 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation.
 Contributed by the Spaces project.
 
 This file is part of the MPFR Library.
@@ -82,9 +82,9 @@ mpfr_exp (mpfr_ptr y, mpfr_srcptr x, mp_rnd_t rnd_mode)
     {
       int signx = MPFR_SIGN(x);
 
+      MPFR_SET_POS(y);
       if (MPFR_IS_NEG_SIGN(signx) && (rnd_mode == GMP_RNDD))
         {
-          MPFR_SET_POS(y);
           mpfr_setmax (y, 0);  /* y = 1 - epsilon */
           return -1;
         }
diff --git a/tests/texp.c b/tests/texp.c
index 0bd81ded1..3ff9acfae 100644
--- a/tests/texp.c
+++ b/tests/texp.c
@@ -31,6 +31,8 @@ check3 (const char *op, mp_rnd_t rnd, const char *res)
   mpfr_t x, y;
 
   mpfr_inits2 (53, x, y, NULL);
+  /* y negative. If we forget to set the sign in mpfr_exp, we'll see it. */
+  mpfr_set_si (y, -1, GMP_RNDN);
   mpfr_set_str1 (x, op);
   mpfr_exp (y, x, rnd);
   if (mpfr_cmp_str1 (y, res) )
@@ -385,6 +387,8 @@ main (int argc, char *argv[])
   compare_exp2_exp3(500);
   check_worst_cases();
   check3("0.0", GMP_RNDU, "1.0");
+  check3("-1e-170", GMP_RNDU, "1.0");
+  check3("-1e-170", GMP_RNDN, "1.0");
   check3("-8.88024741073346941839e-17", GMP_RNDU, "1.0");
   check3("8.70772839244701057915e-01", GMP_RNDN, "2.38875626491680437269");
   check3("1.0", GMP_RNDN, "2.71828182845904509080");