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Implement atanh based on FreeBSD's /usr/src/lib/msun/src/e_atanh.c

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gingerBill
2021-11-16 14:58:59 +00:00
parent eb8b0d7a03
commit 91408cb21f
1 changed files with 42 additions and 2 deletions
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44
core/math/math.odin
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@@ -1465,8 +1465,48 @@ acosh :: proc "contextless" (y: $T) -> T where intrinsics.type_is_float(T) {
return T(log1p(t + sqrt(2*t + t*t)))
}
atanh :: proc "contextless" (x: $T) -> T where intrinsics.type_is_float(T) {
return 0.5*ln((1+x)/(1-x))
atanh :: proc "contextless" (y: $T) -> T where intrinsics.type_is_float(T) {
// The original C code, the long comment, and the constants
// below are from FreeBSD's /usr/src/lib/msun/src/e_atanh.c
// and came with this notice.
//
// ====================================================
// Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
//
// Developed at SunPro, a Sun Microsystems, Inc. business.
// Permission to use, copy, modify, and distribute this
// software is freely granted, provided that this notice
// is preserved.
// ====================================================
NEAR_ZERO :: 1.0 / (1 << 28)
x := f64(y)
switch {
case x < -1 || x > 1 || is_nan(x):
return T(nan_f64())
case x == 1:
return T(inf_f64(1))
case x == -1:
return T(inf_f64(-1))
}
sign := false
if x < 0 {
x = -x
sign = true
}
temp: f64
switch {
case x < NEAR_ZERO:
temp = x
case x < 0.5:
temp = x + x
temp = 0.5 * log1p(temp + temp*x/(1-x))
case:
temp = 0.5 * log1p((x+x)/(1-x))
}
if sign {
temp = -temp
}
return T(temp)
}
ilogb_f16 :: proc "contextless" (val: f16) -> int {