asinh

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

    asinh — Inverse 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

    See Also

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    User Contributed Notes 2 notes

    up
    -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).xls

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

    Allan Patrick Engel
    Curitiba - Paraná - Brasil
    up
    -2
    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))));
    }
    }
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