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atan2 asin

Last updated: Fri, 26 Jan 2007

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# asinh

(PHP 4 >= 4.1.0, PHP 5)

asinh -- Inverse hyperbolic sine

## Description

float asinh ( float arg )

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

> Замечание: Для Windows-платформ эта функция не реализована.

See also: asin(), acosh(), and atanh().

add a note User Contributed Notes
asinh
snoyes at gmail dot com
27-Dec-2005 07:42
`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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atan2 asin

Last updated: Fri, 26 Jan 2007
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