added test for log(10^n)

git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@1740 280ebfd0-de03-0410-8827-d642c229c3f4

1 files changed, 23 insertions, 1 deletions

diff --git a/tests/tlog10.c b/tests/tlog10.c
index abf9a3089..f86bb9619 100644
--- a/tests/tlog10.c
+++ b/tests/tlog10.c
@@ -1,6 +1,6 @@
 /* Test file for mpfr_log10.
 
-Copyright 2001 Free Software Foundation.
+Copyright 2001, 2002 Free Software Foundation.
 Adapted from tsinh.c.
 
 This file is part of the MPFR Library.
@@ -32,7 +32,29 @@ MA 02111-1307, USA. */
 int
 main (int argc, char *argv[])
 {
+  mpfr_t x, y;
+  unsigned int n;
+
   test_generic (2, 100, 100);
 
+  /* check log10(10^n)=n */
+  mpfr_init2 (x, 53);
+  mpfr_init2 (y, 53);
+  mpfr_set_ui (x, 1, GMP_RNDN);
+
+  for (n=1; n<=15; n++)
+    {
+      mpfr_mul_ui (x, x, 10, GMP_RNDN); /* x = 10^n */
+      mpfr_log10 (y, x, GMP_RNDN);
+      if (mpfr_get_d (y) != (double) n)
+        {
+          fprintf (stderr, "log10(10^n) <> n for n=%u\n", n);
+          exit (1);
+        }
+    }
+
+  mpfr_clear (x);
+  mpfr_clear (y);
+
   return 0;
 }