diff options
| -rw-r--r-- | atan.c | 9 |
1 files changed, 5 insertions, 4 deletions
@@ -247,11 +247,12 @@ mpfr_atan (mpfr_ptr atan, mpfr_srcptr x, mp_rnd_t rnd_mode) MPFR_ZIV_INIT (loop, prec); for (;;) { - /* n0 = ceil(log2(realprec + 2 + 1+ln(2.4)/ln(2))) */ - mp_prec_t sup = MAX (-MPFR_GET_EXP (xp), 0) + 2; - n0 = MPFR_INT_CEIL_LOG2 (realprec + sup + 3); + /* First, if |x| < 1, we need to have more prec to be able to round (sup) + n0 = ceil(log(prec_requested + 2 + 1+ln(2.4)/ln(2))/log(2)) */ + mp_prec_t sup = MPFR_GET_EXP (xp) < 0 ? 2-MPFR_GET_EXP (xp) : 1; + n0 = MPFR_INT_CEIL_LOG2 ((realprec + sup) + 3); MPFR_ASSERTD (3*n0 > 2); - prec = realprec + 1 + sup + MPFR_INT_CEIL_LOG2 (3*n0-2); + prec = (realprec + sup) + 1 + MPFR_INT_CEIL_LOG2 (3*n0-2); /* Initialisation */ mpfr_set_prec (sk, prec); |