diff options
Diffstat (limited to 'exp2.c')
| -rw-r--r-- | exp2.c | 26 |
1 files changed, 13 insertions, 13 deletions
@@ -1,4 +1,4 @@ -/* mpfr_exp2 -- power of 2 function 2^y +/* mpfr_exp2 -- power of 2 function 2^y Copyright 2001, 2002, 2003, 2004, 2005 Free Software Foundation. @@ -28,8 +28,8 @@ MA 02110-1301, USA. */ * y = exp(z*log(2)). The result is exact iff z is an integer. */ int -mpfr_exp2 (mpfr_ptr y, mpfr_srcptr x, mp_rnd_t rnd_mode) -{ +mpfr_exp2 (mpfr_ptr y, mpfr_srcptr x, mp_rnd_t rnd_mode) +{ int inexact; MPFR_SAVE_EXPO_DECL (expo); @@ -55,7 +55,7 @@ mpfr_exp2 (mpfr_ptr y, mpfr_srcptr x, mp_rnd_t rnd_mode) return mpfr_set_ui (y, 1, rnd_mode); } } - + /* since the smallest representable non-zero float is 1/2*2^__gmpfr_emin, if x < __gmpfr_emin - 1, the result is either 1/2*2^__gmpfr_emin or 0 */ MPFR_ASSERTD (MPFR_EMIN_MIN - 2 >= LONG_MIN); @@ -73,13 +73,13 @@ mpfr_exp2 (mpfr_ptr y, mpfr_srcptr x, mp_rnd_t rnd_mode) if (mpfr_integer_p (x)) /* we know that x >= 2^(emin-1) */ { long xd; - + MPFR_ASSERTD (MPFR_EMAX_MAX <= LONG_MAX); if (mpfr_cmp_si_2exp (x, __gmpfr_emax, 0) > 0) return mpfr_overflow (y, rnd_mode, 1); - + xd = mpfr_get_si (x, GMP_RNDN); - + mpfr_set_ui (y, 1, GMP_RNDZ); return mpfr_mul_2si (y, y, xd, rnd_mode); } @@ -90,7 +90,7 @@ mpfr_exp2 (mpfr_ptr y, mpfr_srcptr x, mp_rnd_t rnd_mode) { /* Declaration of the intermediary variable */ mpfr_t t; - + /* Declaration of the size variable */ mp_prec_t Ny = MPFR_PREC(y); /* target precision */ mp_prec_t Nt; /* working precision */ @@ -100,10 +100,10 @@ mpfr_exp2 (mpfr_ptr y, mpfr_srcptr x, mp_rnd_t rnd_mode) /* compute the precision of intermediary variable */ /* the optimal number of bits : see algorithms.tex */ Nt = Ny + 5 + MPFR_INT_CEIL_LOG2 (Ny); - + /* initialise of intermediary variable */ mpfr_init2 (t, Nt); - + /* First computation */ MPFR_ZIV_INIT (loop, Nt); for (;;) @@ -113,10 +113,10 @@ mpfr_exp2 (mpfr_ptr y, mpfr_srcptr x, mp_rnd_t rnd_mode) mpfr_mul (t, x, t, GMP_RNDU); /* x*ln(2) */ err = Nt - (MPFR_GET_EXP (t) + 2); /* Estimate of the error */ mpfr_exp (t, t, GMP_RNDN); /* exp(x*ln(2))*/ - + if (MPFR_LIKELY (MPFR_CAN_ROUND (t, err, Ny, rnd_mode))) break; - + /* Actualisation of the precision */ MPFR_ZIV_NEXT (loop, Nt); mpfr_set_prec (t, Nt); @@ -124,7 +124,7 @@ mpfr_exp2 (mpfr_ptr y, mpfr_srcptr x, mp_rnd_t rnd_mode) MPFR_ZIV_FREE (loop); inexact = mpfr_set (y, t, rnd_mode); - + mpfr_clear (t); } MPFR_SAVE_EXPO_FREE (expo); |