math: cosh cleanup

[musl] / src / math / coshf.c

diff --git a/src/math/coshf.c b/src/math/coshf.c
index 97318f1..2bed125 100644 (file)
--- a/src/math/coshf.c
+++ b/src/math/coshf.c
@@ -15,43 +15,40 @@
 
 #include "libm.h"
 
-static const float huge = 1.0e30;
-
 float coshf(float x)
 {
-       float t, w;
-       int32_t ix;
-
-       GET_FLOAT_WORD(ix, x);
-       ix &= 0x7fffffff;
+       union {float f; uint32_t i;} u = {.f = x};
+       uint32_t ix;
+       float t;
 
-       /* x is INF or NaN */
-       if (ix >= 0x7f800000)
-               return x*x;
+       /* |x| */
+       u.i &= 0x7fffffff;
+       x = u.f;
+       ix = u.i;
 
        /* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */
        if (ix < 0x3eb17218) {
-               t = expm1f(fabsf(x));
-               w = 1.0f+t;
-               if (ix<0x39800000)
-                       return 1.0f;  /* cosh(tiny) = 1 */
-               return 1.0f + (t*t)/(w+w);
+               t = expm1f(x);
+               if (ix < 0x39800000)
+                       return 1;
+               return 1 + t*t/(2*(1+t));
        }
 
        /* |x| in [0.5*ln2,9], return (exp(|x|)+1/exp(|x|))/2; */
        if (ix < 0x41100000) {
-               t = expf(fabsf(x));
+               t = expf(x);
                return 0.5f*t + 0.5f/t;
        }
 
        /* |x| in [9, log(maxfloat)] return 0.5f*exp(|x|) */
        if (ix < 0x42b17217)
-               return 0.5f*expf(fabsf(x));
+               return 0.5f*expf(x);
 
        /* |x| in [log(maxfloat), overflowthresold] */
        if (ix <= 0x42b2d4fc)
-               return __expo2f(fabsf(x));
+               return __expo2f(x);
 
-       /* |x| > overflowthresold, cosh(x) overflow */
-       return huge*huge;
+       /* |x| > overflowthresold or nan */
+       x *= 0x1p127f;
+       return x;
 }