diff options
Diffstat (limited to 'pow.c')
| -rw-r--r-- | pow.c | 8 |
1 files changed, 5 insertions, 3 deletions
@@ -538,6 +538,8 @@ mpfr_pow (mpfr_ptr z, mpfr_srcptr x, mpfr_srcptr y, mp_rnd_t rnd_mode) } } + /* FIXME: basic underflow checking is incomplete. This is needed + for the special case (+/-2^b)^Y below. */ /* detect underflows: for x > 0, y < 0, |x^y| = |(1/x)^(-y)| <= 2^((1-EXP(x))*(-y)) */ if (MPFR_IS_NEG(y) && MPFR_EXP(x) > 1) @@ -602,9 +604,9 @@ mpfr_pow (mpfr_ptr z, mpfr_srcptr x, mpfr_srcptr y, mp_rnd_t rnd_mode) inexact = mpfr_mul_si (tmp, y, b, GMP_RNDN); /* exact */ MPFR_ASSERTN (inexact == 0); /* Note: as the exponent range has been extended, an overflow is not - possible (due to basic overflow checking above, as the result is - ~ 2^tmp), and an underflow is not possible either because b is an - integer (thus either 0 or >= 1). */ + possible (due to basic overflow and underflow checking above, as + the result is ~ 2^tmp), and an underflow is not possible either + because b is an integer (thus either 0 or >= 1). */ mpfr_clear_flags (); inexact = mpfr_exp2 (z, tmp, rnd_mode); mpfr_clear (tmp); |