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  • asinh()

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

    反双曲正弦

    说明

    asinh(float $arg):float

    返回$arg的反双曲正弦值,即,其双曲正弦为$arg的那个值。

    参数

    $arg

    要处理的参数

    返回值

    返回$arg的反双曲正弦值

    更新日志

    版本说明
    5.3.0此函数在所有平台上均可用

    参见

    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
    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))));
      }
    }

    上篇:asin()

    下篇:atan2()