# asinh

(PHP 4 >= 4.1.0, PHP 5, PHP 7)

asinh역쌍곡사인

### 설명

float asinh ( float `\$arg` )

`arg`의 역쌍곡사인 값을 반환합니다. 즉, 반환값의 쌍곡사인은 `arg`가 됩니다.

`arg`

계산할 인수

### 반환값

`arg`의 역쌍곡사인

### 변경점

버전 설명
5.3.0 모든 플랫폼에서 이 함수를 사용할 수 있게 되었습니다.

### 참고

``` 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).xlsThis implementation using LN, give THE SAME results that function asinh(x) linux native.Allan Patrick EngelCuritiba - 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))));    }} ```