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(PHP 4 >= 4.1.0, PHP 5)

asinhInverse hyperbolic sine


float asinh ( float $arg )

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



The argument to process

Valorile întoarse

The inverse hyperbolic sine of arg

Istoria schimbărilor

Versiunea Descriere
5.3.0 This function is now available on all platforms

Vedeți de asemenea

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User Contributed Notes 2 notes

ape_cwb at yahoo dot com dot br
6 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
8 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))));
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