| Index: fusl/src/math/log1pf.c
|
| diff --git a/fusl/src/math/log1pf.c b/fusl/src/math/log1pf.c
|
| index 23985c35675842d925bbc3c1475bd419926e0fda..e50ad823ae6e6aa5a1c946c11374fc22f5951cb0 100644
|
| --- a/fusl/src/math/log1pf.c
|
| +++ b/fusl/src/math/log1pf.c
|
| @@ -12,66 +12,67 @@
|
|
|
| #include "libm.h"
|
|
|
| -static const float
|
| -ln2_hi = 6.9313812256e-01, /* 0x3f317180 */
|
| -ln2_lo = 9.0580006145e-06, /* 0x3717f7d1 */
|
| -/* |(log(1+s)-log(1-s))/s - Lg(s)| < 2**-34.24 (~[-4.95e-11, 4.97e-11]). */
|
| -Lg1 = 0xaaaaaa.0p-24, /* 0.66666662693 */
|
| -Lg2 = 0xccce13.0p-25, /* 0.40000972152 */
|
| -Lg3 = 0x91e9ee.0p-25, /* 0.28498786688 */
|
| -Lg4 = 0xf89e26.0p-26; /* 0.24279078841 */
|
| +static const float ln2_hi = 6.9313812256e-01, /* 0x3f317180 */
|
| + ln2_lo = 9.0580006145e-06, /* 0x3717f7d1 */
|
| + /* |(log(1+s)-log(1-s))/s - Lg(s)| < 2**-34.24 (~[-4.95e-11, 4.97e-11]). */
|
| + Lg1 = 0xaaaaaa.0p-24, /* 0.66666662693 */
|
| + Lg2 = 0xccce13.0p-25, /* 0.40000972152 */
|
| + Lg3 = 0x91e9ee.0p-25, /* 0.28498786688 */
|
| + Lg4 = 0xf89e26.0p-26; /* 0.24279078841 */
|
|
|
| -float log1pf(float x)
|
| -{
|
| - union {float f; uint32_t i;} u = {x};
|
| - float_t hfsq,f,c,s,z,R,w,t1,t2,dk;
|
| - uint32_t ix,iu;
|
| - int k;
|
| +float log1pf(float x) {
|
| + union {
|
| + float f;
|
| + uint32_t i;
|
| + } u = {x};
|
| + float_t hfsq, f, c, s, z, R, w, t1, t2, dk;
|
| + uint32_t ix, iu;
|
| + int k;
|
|
|
| - ix = u.i;
|
| - k = 1;
|
| - if (ix < 0x3ed413d0 || ix>>31) { /* 1+x < sqrt(2)+ */
|
| - if (ix >= 0xbf800000) { /* x <= -1.0 */
|
| - if (x == -1)
|
| - return x/0.0f; /* log1p(-1)=+inf */
|
| - return (x-x)/0.0f; /* log1p(x<-1)=NaN */
|
| - }
|
| - if (ix<<1 < 0x33800000<<1) { /* |x| < 2**-24 */
|
| - /* underflow if subnormal */
|
| - if ((ix&0x7f800000) == 0)
|
| - FORCE_EVAL(x*x);
|
| - return x;
|
| - }
|
| - if (ix <= 0xbe95f619) { /* sqrt(2)/2- <= 1+x < sqrt(2)+ */
|
| - k = 0;
|
| - c = 0;
|
| - f = x;
|
| - }
|
| - } else if (ix >= 0x7f800000)
|
| - return x;
|
| - if (k) {
|
| - u.f = 1 + x;
|
| - iu = u.i;
|
| - iu += 0x3f800000 - 0x3f3504f3;
|
| - k = (int)(iu>>23) - 0x7f;
|
| - /* correction term ~ log(1+x)-log(u), avoid underflow in c/u */
|
| - if (k < 25) {
|
| - c = k >= 2 ? 1-(u.f-x) : x-(u.f-1);
|
| - c /= u.f;
|
| - } else
|
| - c = 0;
|
| - /* reduce u into [sqrt(2)/2, sqrt(2)] */
|
| - iu = (iu&0x007fffff) + 0x3f3504f3;
|
| - u.i = iu;
|
| - f = u.f - 1;
|
| - }
|
| - s = f/(2.0f + f);
|
| - z = s*s;
|
| - w = z*z;
|
| - t1= w*(Lg2+w*Lg4);
|
| - t2= z*(Lg1+w*Lg3);
|
| - R = t2 + t1;
|
| - hfsq = 0.5f*f*f;
|
| - dk = k;
|
| - return s*(hfsq+R) + (dk*ln2_lo+c) - hfsq + f + dk*ln2_hi;
|
| + ix = u.i;
|
| + k = 1;
|
| + if (ix < 0x3ed413d0 || ix >> 31) { /* 1+x < sqrt(2)+ */
|
| + if (ix >= 0xbf800000) { /* x <= -1.0 */
|
| + if (x == -1)
|
| + return x / 0.0f; /* log1p(-1)=+inf */
|
| + return (x - x) / 0.0f; /* log1p(x<-1)=NaN */
|
| + }
|
| + if (ix << 1 < 0x33800000 << 1) { /* |x| < 2**-24 */
|
| + /* underflow if subnormal */
|
| + if ((ix & 0x7f800000) == 0)
|
| + FORCE_EVAL(x * x);
|
| + return x;
|
| + }
|
| + if (ix <= 0xbe95f619) { /* sqrt(2)/2- <= 1+x < sqrt(2)+ */
|
| + k = 0;
|
| + c = 0;
|
| + f = x;
|
| + }
|
| + } else if (ix >= 0x7f800000)
|
| + return x;
|
| + if (k) {
|
| + u.f = 1 + x;
|
| + iu = u.i;
|
| + iu += 0x3f800000 - 0x3f3504f3;
|
| + k = (int)(iu >> 23) - 0x7f;
|
| + /* correction term ~ log(1+x)-log(u), avoid underflow in c/u */
|
| + if (k < 25) {
|
| + c = k >= 2 ? 1 - (u.f - x) : x - (u.f - 1);
|
| + c /= u.f;
|
| + } else
|
| + c = 0;
|
| + /* reduce u into [sqrt(2)/2, sqrt(2)] */
|
| + iu = (iu & 0x007fffff) + 0x3f3504f3;
|
| + u.i = iu;
|
| + f = u.f - 1;
|
| + }
|
| + s = f / (2.0f + f);
|
| + z = s * s;
|
| + w = z * z;
|
| + t1 = w * (Lg2 + w * Lg4);
|
| + t2 = z * (Lg1 + w * Lg3);
|
| + R = t2 + t1;
|
| + hfsq = 0.5f * f * f;
|
| + dk = k;
|
| + return s * (hfsq + R) + (dk * ln2_lo + c) - hfsq + f + dk * ln2_hi;
|
| }
|
|
|