------- Comment #4 from burnus at gcc dot gnu dot org 2007-11-22 17:08 ------- Regarding the range check: We need to disable the check for denormal numbers; as overflow etc. cannot occur, this boils down to check only for NaN.
Regarding the result, I think we have a problem with MPFR. The following program prints: Result (GMP_RNDN): 0 Result (GMP_RNDU): 4.94066e-324 As mpfr_nexttoward should return a representable number, there should be no rounding needed, or should it? By the way, changing GFC_REAL_8_DIGITS did not change the result. See also: http://www.mpfr.org/mpfr-2.3.0/mpfr.html#index-mpfr_005fnexttoward-224 #include <gmp.h> #include <mpfr.h> #include <stdio.h> #define GFC_REAL_8_DIGITS 53 int main() { mpfr_t x; mpfr_t y; int base2prec; double result; mpfr_set_default_prec (GFC_REAL_8_DIGITS); mpfr_init(x); mpfr_init(y); mpfr_set_d (x, 0.0, GMP_RNDN); /* x = 0.0 */ mpfr_set_inf (y, 1); /* y = INF */ mpfr_nexttoward (x, y); /* x = x + epsilon */ printf("Result (GMP_RNDN): %g\n", mpfr_get_d(x, GMP_RNDN)); printf("Result (GMP_RNDU): %g\n", mpfr_get_d(x, GMP_RNDU)); return 0; } -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34192
