# asinh

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

asinhInverse hyperbolic sine

### Descrierea

float asinh ( float \$arg )

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

### Parametri

arg

The argument to process

### Valorile întoarse

The inverse hyperbolic sine of arg

### Istoricul schimbărilor

Versiune Descriere
5.3.0 This function is now available on all platforms

### User Contributed Notes 2 notes

ape_cwb at yahoo dot com dot br
10 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)

This implementation using LN, give THE SAME results that function asinh(x) linux native.

Allan Patrick Engel
Curitiba - Paraná - Brasil
snoyes at gmail dot com
12 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) {