fn acosh64(x: f64) f64 x: f6444
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60fn acosh64(x: f64) f64 {
const u = @as(u64, @bitCast(x));
const e = (u >> 52) & 0x7FF;
// |x| < 2, invalid if x < 1 or nan
if (e < 0x3FF + 1) {
return math.log1p(x - 1 + @sqrt((x - 1) * (x - 1) + 2 * (x - 1)));
}
// |x| < 0x1p26
else if (e < 0x3FF + 26) {
return @log(2 * x - 1 / (x + @sqrt(x * x - 1)));
}
// |x| >= 0x1p26 or nan
else {
return @log(x) + 0.693147180559945309417232121458176568;
}
}