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; |
} |