abs() returns negative value? why?

Can you please tell me what is wrong in the image below?

I just don’t see how abs() from a scalar can return a negative value?

You are probably taking the log10 of 0. Taking the log of 0 is equally invalid.

Understandably, the error message is confusing. I raised a bug report for that: https://gitlab.kitware.com/paraview/paraview/issues/18322

Ah, so switching “replace invalid results” mode should produce more or less adequate effect?
That’s all right. Thank you for responding so promptly!

Yes, that seemed to work for me. But you might consider also changing the Replacement Value field from 0 to some low negative number. Remember that log of a number less than 1 (but greater than 0) is negative, so it would be best that whatever the calculator replaces 0’s with is less than other expected values.