diff options
Diffstat (limited to 'sysdeps/libm-ieee754/e_exp.c')
| -rw-r--r-- | sysdeps/libm-ieee754/e_exp.c | 48 |
1 files changed, 15 insertions, 33 deletions
diff --git a/sysdeps/libm-ieee754/e_exp.c b/sysdeps/libm-ieee754/e_exp.c index 660c5bc88d..5eae12a19c 100644 --- a/sysdeps/libm-ieee754/e_exp.c +++ b/sysdeps/libm-ieee754/e_exp.c @@ -76,8 +76,8 @@ __ieee754_exp (double x) /* Check for usual case. */ if (isless (x, himark) && isgreater (x, lomark)) { - static const double TWO43 = 8796093022208.0; - static const double TWO52 = 4503599627370496.0; + static const double THREEp42 = 13194139533312.0; + static const double THREEp51 = 6755399441055744.0; /* 1/ln(2). */ static const double M_1_LN2 = 1.442695040888963387; /* ln(2), part 1 */ @@ -94,40 +94,22 @@ __ieee754_exp (double x) fesetround (FE_TONEAREST); /* Calculate n. */ - if (x >= 0) - { - n = x * M_1_LN2 + TWO52; - n -= TWO52; - } - else - { - n = x * M_1_LN2 - TWO52; - n += TWO52; - } + n = x * M_1_LN2 + THREEp51; + n -= THREEp51; x = x - n*M_LN2_0; - if (x >= 0) - { - /* Calculate t/512. */ - t = x + TWO43; - t -= TWO43; - x -= t; - - /* Compute tval = t. */ - tval = (int) (t * 512.0); - - x -= __exp_deltatable[tval]; - } - else - { - /* As above, but x is negative. */ - t = x - TWO43; - t += TWO43; - x -= t; - tval = (int) (t * 512.0); + /* Calculate t/512. */ + t = x + THREEp42; + t -= THREEp42; + x -= t; - x += __exp_deltatable[-tval]; - } + /* Compute tval = t. */ + tval = (int) (t * 512.0); + + if (t >= 0) + x -= __exp_deltatable[tval]; + else + x += __exp_deltatable[-tval]; /* Now, the variable x contains x + n*ln(2)_1. */ dely = n*M_LN2_1; |