Fixed an issue with mpfr_get_str: The number 1 of significant digits

output in the string is now fully supported, i.e.
  * the value 1 can be provided for n (4th argument);
  * if n = 0, then the number of significant digits in the output string
    can now be 1, as already implied by the documentation (but the code
    was increasing it to 2).
Changes:
  * doc/mpfr.texi: updated mpfr_get_str description to accept n = 1.
  * src/get_str.c: fixed the code as explained above (for n = 0,
    removed the increase to 2, and removed an MPFR_ASSERTN).
  * tests/tget_str.c: added tests.
(merged changesets from the trunk: r12430 on tests/tget_str.c only;
r12432,12434,12440)

git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/branches/4.0@12642 280ebfd0-de03-0410-8827-d642c229c3f4

1 files changed, 36 insertions, 0 deletions

diff --git a/tests/tget_str.c b/tests/tget_str.c
index b49d3a013..2ede2c07e 100644
--- a/tests/tget_str.c
+++ b/tests/tget_str.c
@@ -1267,6 +1267,41 @@ check_negative_base (void)
 
 #define ITER 1000
 
+static void
+coverage (void)
+{
+  mpfr_t x;
+  char s[42];
+  mpfr_exp_t e;
+  int b = 3;
+  size_t m = 40;
+
+  mpfr_init2 (x, 128);
+
+  /* exercise corner case in mpfr_get_str_aux: exact case (e < 0), where r
+     rounds to a power of 2, and f is a multiple of GMP_NUMB_BITS */
+  mpfr_set_ui_2exp (x, 1, 64, MPFR_RNDU);
+  mpfr_nextbelow (x);
+  /* x = 2^64 - 2^(-64) */
+  mpfr_get_str (s, &e, b, m, x, MPFR_RNDU);
+  /* s is the base-3 string for 6148914691236517206 (in base 10) */
+  MPFR_ASSERTN(strcmp (s, "1111222002212212010121102012021021021200") == 0);
+  MPFR_ASSERTN(e == 41);
+
+  /* exercise corner case in mpfr_get_str: input is m=0, then it is changed
+     to m=1 */
+  mpfr_set_prec (x, 1);
+  mpfr_set_ui (x, 1, MPFR_RNDN);
+  mpfr_get_str (s, &e, 2, 0, x, MPFR_RNDN);
+  MPFR_ASSERTN(strcmp (s, "1") == 0);
+  MPFR_ASSERTN(e == 1);
+  mpfr_get_str (s, &e, 2, 1, x, MPFR_RNDN);
+  MPFR_ASSERTN(strcmp (s, "1") == 0);
+  MPFR_ASSERTN(e == 1);
+
+  mpfr_clear (x);
+}
+
 int
 main (int argc, char *argv[])
 {
@@ -1281,6 +1316,7 @@ main (int argc, char *argv[])
 
   tests_start_mpfr ();
 
+  coverage ();
   check_small ();
 
   check_special (2, 2);