[tests]

  * tests.c, function bad_cases(): updated/added debug messages;
    assume that the parameters are chosen in such a way that this
    test always generates hard-to-round cases (including exact cases),
    i.e. exit with an error if one does not get a bad case, otherwise
    this can leave unexpected failures unnoticed (either due to a bug
    in the MPFR library or due to poorly chosen parameters such as in
    troot.c until now).
    Note: ideally, this would require a proof, but it is better to get
    (unlikely) spurious failures with a non-default GMP_CHECK_RANDOMIZE
    value than missing important tests.
  * troot.c, bad_cases() invocation:
      - corrected the pos parameter: when n is even, it is useless to
        generate a negative number as the function is not defined (the
        inverse function generates a positive number, and the mismatch
        now yields a failure due to the change in bad_cases); when n is
        odd, generate as many negative numbers as positive ones.
      - for n ≤ 5, reduce the psup parameter in order to also generate
        inexact cases, instead of always exact cases.

git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@13783 280ebfd0-de03-0410-8827-d642c229c3f4

2 files changed, 15 insertions, 10 deletions

diff --git a/tests/tests.c b/tests/tests.c
index fd62540ca..579da8735 100644
--- a/tests/tests.c
+++ b/tests/tests.c
@@ -997,7 +997,7 @@ bad_cases (int (*fct)(FLIST), int (*inv)(FLIST), const char *name,
       int inex;
 
       if (dbg)
-        printf ("bad_cases: i = %d\n", i);
+        printf ("bad_cases: %s, i = %d\n", name, i);
       py = pymin + (randlimb () % (pymax - pymin + 1));
       mpfr_set_prec (y, py);
       tests_default_random (y, pos, emin, emax, 0);
@@ -1009,6 +1009,8 @@ bad_cases (int (*fct)(FLIST), int (*inv)(FLIST), const char *name,
         }
       px = py + psup;
       mpfr_set_prec (x, px);
+      if (dbg)
+        printf ("bad_cases: xprec =%4ld\n", (long) px);
       mpfr_clear_flags ();
       inv (x, y, MPFR_RNDN);
       if (mpfr_nanflag_p () || mpfr_overflow_p () || mpfr_underflow_p ())
@@ -1055,9 +1057,12 @@ bad_cases (int (*fct)(FLIST), int (*inv)(FLIST), const char *name,
           if (mpfr_nanflag_p () || mpfr_overflow_p () || mpfr_underflow_p ()
               || ! mpfr_equal_p (z, y))
             {
-              if (dbg)
-                printf ("bad_cases: inverse doesn't match\n");
-              goto next_i;
+              printf ("bad_cases: inverse doesn't match for %s\ny = ", name);
+              mpfr_out_str (stdout, 16, 0, y, MPFR_RNDN);
+              printf ("\nz = ");
+              mpfr_out_str (stdout, 16, 0, z, MPFR_RNDN);
+              printf ("\n");
+              exit (1);
             }
         }
       while (inex == 0);
diff --git a/tests/troot.c b/tests/troot.c
index 436b75c9c..c7d9075e8 100644
--- a/tests/troot.c
+++ b/tests/troot.c
@@ -590,12 +590,12 @@ main (int argc, char *argv[])
 
   test_generic_ui (MPFR_PREC_MIN, 200, 30);
 
-  bad_cases (root2, pow2, "rootn[2]", 8, -256, 255, 4, 128, 800, 40);
-  bad_cases (root3, pow3, "rootn[3]", 8, -256, 255, 4, 128, 800, 40);
-  bad_cases (root4, pow4, "rootn[4]", 8, -256, 255, 4, 128, 800, 40);
-  bad_cases (root5, pow5, "rootn[5]", 8, -256, 255, 4, 128, 800, 40);
-  bad_cases (root17, pow17, "rootn[17]", 8, -256, 255, 4, 128, 800, 40);
-  bad_cases (root120, pow120, "rootn[120]", 8, -256, 255, 4, 128, 800, 40);
+  bad_cases (root2, pow2, "rootn[2]", 0, -256, 255, 4, 128, 80, 40);
+  bad_cases (root3, pow3, "rootn[3]", 256, -256, 255, 4, 128, 200, 40);
+  bad_cases (root4, pow4, "rootn[4]", 0, -256, 255, 4, 128, 320, 40);
+  bad_cases (root5, pow5, "rootn[5]", 256, -256, 255, 4, 128, 440, 40);
+  bad_cases (root17, pow17, "rootn[17]", 256, -256, 255, 4, 128, 800, 40);
+  bad_cases (root120, pow120, "rootn[120]", 0, -256, 255, 4, 128, 800, 40);
 
   tests_end_mpfr ();
   return 0;