Unable to execute formula for member "xxx'. Value was either too large or too small for a Decimal.

It seems to be failing at the exponent part of this approach (Dim z).  What is odd, it looks like  negative value is causing an issue. Testing a Dim with an abs() renders.  I guess I could do "IF" logic to adjust, but that's odd to me that I couldn't leverage a negative value on an exponent double?

See examples below:

Dim Double

Result: No longer and error message, but noData being returned.

Making the base value ABS

Result Renders (obviously not the math I want, but the calc runs)