PHP Source:
<
!DOCTYPE
html
>
<
html
>
<
body
>
<?php
echo
(atanh(M_PI_4) .
"<br>"
);
echo
(atanh(
0.50
) .
"<br>"
);
echo
(atanh(-
0.50
) .
"<br>"
);
echo
(atanh(
1
) .
"<br>"
);
echo
(atanh(-
1
));
?>
<
/body
>
<
/html
>
Result: