[gradsusr] pow() function with negative exponent - unusual behavior

L.B. bcbass2989 at gmail.com
Thu Jan 9 13:41:19 EST 2020


I am having an issue with the pow() function using a negative exponent. It
is displaying a constant field where it should be a variable field. I have
attached the grib file as well as the ctl file and all relevant equations
are below:

The grib file contains the precipitation rate. I am trying to create a
field which uses the precip rate as follows:

*'define prate = (pratesfc/25.4)*3600'   **Converting the precip rate field
to in/hr*

Plotting this yields a varying precip rate field in inches/hour.

Next, I want to apply the following equation to the prate field:

*'d 0.1*pow(prate,-0.54)'*

The issue is that it creates a constant field with a value of 0.0563103
when it should still be a varying field. Is this a bug with pow() function,
or is something else going on here?

William LaForce IV
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