asinh()
(PHP 4 >= 4.1.0, PHP 5, PHP 7)
反双曲正弦
说明
asinh(float $arg):float
返回$arg的反双曲正弦值,即,其双曲正弦为$arg的那个值。
参数
- $arg
要处理的参数
返回值
返回$arg的反双曲正弦值
更新日志
版本 | 说明 |
---|---|
5.3.0 | 此函数在所有平台上均可用 |
参见
The correct implementation of asinh(x) for Windows plataform is: ------------------------------------------------------- function asinh($x) { return ln($x + sqrt(1 + pow($x, 2))); } function ln($x) { return $x = log($x)/log(M_E); } -------------------------------------------------------- The worksheet above includes a comparation about the native asinh(x) and the implemented version using LN and LOG (like Snoyes posted on 27-Dec-2005 07:42) http://www.mavadesign.com.br/allan/asinh(x).xls This implementation using LN, give THE SAME results that function asinh(x) linux native. Allan Patrick Engel Curitiba - Paraná - Brasil
asinh for windows: The definition for asinh is asinh(z) = log(z + sqrt(z^2 + 1)) The built-in math functions and operators give poor results for small values of z. The BCMath version produces closer results, but still quite distant if z < 1. A BCMath version of the log function might help. if (!function_exists("asinh")) { function asinh($z) { return log($z + sqrt($z^2 +1)); } } if (!function_exists("bcasinh")) { function bcasinh($z) { return log(bcadd($z, bcsqrt(bcadd(bcpow($z, 2), 1)))); } }