How do I calculate the square root of a negative number?

Some calculations may require you to calculate the square root of a negative number due to the previously calculated or defined values but this will result in an expression error. A possible workaround is to compare the calculated value with a very small number and the square root the maximum of the two.

Here's a very simple example:

works OK if ‘x’ is positive
x = 200
y = 20
z = SQRT(x/y) = 3.162

but there’s an error if ‘x’ is negative
x = -200
y = 20
z = SQRT(x/y) = ? <Error: numeric range error>

Workaround

x = 200
y = 20
z = SQRT( max( x/y , 0.0001 )) = 3.162

x = -200
y = 20
z = SQRT( max( x/y , 0.0001 )) = 0.010