123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778 |
- package math
- func Atanh(x float64) float64 {
- const NearZero = 1.0 / (1 << 28)
-
- switch {
- case x < -1 || x > 1 || IsNaN(x):
- return NaN()
- case x == 1:
- return Inf(1)
- case x == -1:
- return Inf(-1)
- }
- sign := false
- if x < 0 {
- x = -x
- sign = true
- }
- var temp float64
- switch {
- case x < NearZero:
- temp = x
- case x < 0.5:
- temp = x + x
- temp = 0.5 * Log1p(temp+temp*x/(1-x))
- default:
- temp = 0.5 * Log1p((x+x)/(1-x))
- }
- if sign {
- temp = -temp
- }
- return temp
- }
|