diff options
Diffstat (limited to 'sysdeps/libm-ieee754/e_expf.c')
| -rw-r--r-- | sysdeps/libm-ieee754/e_expf.c | 48 |
1 files changed, 15 insertions, 33 deletions
diff --git a/sysdeps/libm-ieee754/e_expf.c b/sysdeps/libm-ieee754/e_expf.c index c4a7b644fd..ff6357bd1d 100644 --- a/sysdeps/libm-ieee754/e_expf.c +++ b/sysdeps/libm-ieee754/e_expf.c @@ -71,8 +71,8 @@ __ieee754_expf (float x) /* Check for usual case. */ if (isless (x, himark) && isgreater (x, lomark)) { - static const float TWO43 = 8796093022208.0; - static const float TWO23 = 8388608.0; + static const float THREEp42 = 13194139533312.0; + static const float THREEp22 = 12582912.0; /* 1/ln(2). */ #undef M_1_LN2 static const float M_1_LN2 = 1.44269502163f; @@ -90,40 +90,22 @@ __ieee754_expf (float x) fesetround (FE_TONEAREST); /* Calculate n. */ - if (x >= 0) - { - n = x * M_1_LN2 + TWO23; - n -= TWO23; - } - else - { - n = x * M_1_LN2 - TWO23; - n += TWO23; - } + n = x * M_1_LN2 + THREEp22; + n -= THREEp22; dx = x - n*M_LN2; - if (dx >= 0) - { - /* Calculate t/512. */ - t = dx + TWO43; - t -= TWO43; - dx -= t; - - /* Compute tval = t. */ - tval = (int) (t * 512.0); - - delta = - __exp_deltatable[tval]; - } - else - { - /* As above, but x is negative. */ - t = dx - TWO43; - t += TWO43; - dx -= t; - tval = (int) (t * 512.0); + /* Calculate t/512. */ + t = dx + THREEp42; + t -= THREEp42; + dx -= t; - delta = __exp_deltatable[-tval]; - } + /* Compute tval = t. */ + tval = (int) (t * 512.0); + + if (t >= 0) + delta = - __exp_deltatable[tval]; + else + delta = __exp_deltatable[-tval]; /* Compute ex2 = 2^n e^(t/512+delta[t]). */ ex2_u.d = __exp_atable[tval+177]; |