# PHP atanh() Function

## Definition and Usage

The atanh() function returns the inverse hyperbolic tangent ratio of given given parameter. In other words, the return value of atanh() is hyperbolic tangent of given parameter. A inverse hyperbolic tangent function is defined as .

atanh(x) = 0.5Xlog((1+x)/(1-x))

This function returns a float value .

atanh ( float $arg ) : float ## Parameters Sr.NoParameter & Description 1arg A floating point value whose inverse hyperbolic tangent is to be calculated ## Return Values PHP atanh() function returns inverse hyperbolic tangent ratio of given parameter. ## PHP Version This function is available in PHP versions 4.x, PHP 5.x as well as PHP 7.x. ## Example Live Demo Following example calculates atanh(pi/4) and returns which is also the result of formula definition − <?php$arg=M_PI_4;
$res=atanh($arg);
echo "atanh(pi) = " . $res . "";$val = 0.5*log((1+$arg)/(1-$arg));
echo "using formula = " . $val; ?> ## Output This will produce following result − atanh(pi) = 1.0593061708232 using formula = 1.0593061708232 ## Example Live Demo Following example computes atanh(Π/10) − <?php$arg=M_PI/10;;
$val=atanh($arg);
echo "atanh(" . $arg . ") = " .$val;
?>

## Output

This will produce following result −

atanh(0.31415926535898) = 0.32515348134414

## Example

Live Demo

Let's check find out atanh(0). It returns 0 −

<?php
$arg=0;$val=atanh($arg); echo "atanh(" .$arg . ") = " . $val; ?> ## Output This will produce following result − atanh(0) = 0 ## Example Live Demo For parameter = 1 atanh() function returns INF <?php$arg=1;
$val=atanh($arg);
echo "atanh(" . $arg . ") = " .$val;
?>

## Output

This will produce following result −

atanh(1) = INF

Updated on: 29-Jun-2020

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