diff options
Diffstat (limited to 'src/math/atan.c')
| -rw-r--r-- | src/math/atan.c | 32 |
1 files changed, 13 insertions, 19 deletions
diff --git a/src/math/atan.c b/src/math/atan.c index f34551c7..7fd8a3b8 100644 --- a/src/math/atan.c +++ b/src/math/atan.c @@ -60,32 +60,26 @@ static const double aT[] = { 1.62858201153657823623e-02, /* 0x3F90AD3A, 0xE322DA11 */ }; -static const double huge = 1.0e300; - double atan(double x) { double w,s1,s2,z; - int32_t ix,hx,id; + uint32_t ix,sign; + int id; - GET_HIGH_WORD(hx, x); - ix = hx & 0x7fffffff; + GET_HIGH_WORD(ix, x); + sign = ix >> 31; + ix &= 0x7fffffff; if (ix >= 0x44100000) { /* if |x| >= 2^66 */ - uint32_t low; - - GET_LOW_WORD(low, x); - if (ix > 0x7ff00000 || - (ix == 0x7ff00000 && low != 0)) /* NaN */ - return x+x; - if (hx > 0) - return atanhi[3] + *(volatile double *)&atanlo[3]; - else - return -atanhi[3] - *(volatile double *)&atanlo[3]; + if (isnan(x)) + return x; + z = atanhi[3] + 0x1p-1000; + return sign ? -z : z; } if (ix < 0x3fdc0000) { /* |x| < 0.4375 */ if (ix < 0x3e400000) { /* |x| < 2^-27 */ - /* raise inexact */ - if (huge+x > 1.0) - return x; + /* raise inexact if x!=0 */ + FORCE_EVAL(x + 0x1p1000); + return x; } id = -1; } else { @@ -117,5 +111,5 @@ double atan(double x) if (id < 0) return x - x*(s1+s2); z = atanhi[id] - (x*(s1+s2) - atanlo[id] - x); - return hx < 0 ? -z : z; + return sign ? -z : z; } |