PHP Manual: Get the square root of an arbitrary precision number

string bcsqrt(string $num, intnull $scale = null)

Return the square root of num.

num: The operand, as a well-formed BCMath numeric string.
scale: This parameter is used to set the number of digits after the decimal place in the result. If null, it will default to the default scale set with bcscale, or fallback to the value of the bcmath.scale INI directive.

Returns the square root as a well-formed BCMath numeric string.

This function throws a ValueError in the following cases:

Version	Description
8.0.0	If `num` is not a well-formed BCMath numeric string, or less than `0`, a ValueError is thrown. Previously, `E_WARNING` was raised instead.
8.0.0	`scale` now needs to be between `0` and `2147483647`; previously, negative scales have been silently treated as `0`.
8.0.0	`scale` is now nullable.

Example #1 bcsqrt example

<?php

echo bcsqrt('2', 3); // 1.414

?>

bcsqrt