tanh(): Hyperbolic tangent

<?Php
echo tanh(0); // Output is 0
echo "<br>";
echo tanh(1); // Output  0.76159415595576
echo "<br>";
echo tanh(-1); // Output -0.76159415595576
echo "<br>";
echo tanh(4.2); // Output is 0.99955036645953
echo "<br>";
echo tanh(2); // Output is 0.96402758007582
echo "<br>";
echo tanh(90); // Output is 1
?>

float tanh(float $x);

Plotting of SIN & SIN curves by using PHP GD function with deg2rad()