# asinh

(PHP 4 >= 4.1.0, PHP 5, PHP 7, PHP 8)

asinhInverse hyperbolic sine

### Description

asinh(float `\$num`): float

Returns the inverse hyperbolic sine of `num`, i.e. the value whose hyperbolic sine is `num`.

### Parameters

`num`

The argument to process

### Return Values

The inverse hyperbolic sine of `num`

add a note

### User Contributed Notes 2 notes

-1
ape_cwb at yahoo dot com dot br
16 years ago
`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`
-3
snoyes at gmail dot com
18 years ago
`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)))); }}`