Bug fix - Fixes issue if FillValue is NaN

[Benjamin-Gunn]

Fixes #323

Description:

Bug fix for the Nan FillValue.

Fixes issue

Fixes #323

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update

Documentation changes needed?

• My change requires a change to the documentation.
  • I have updated the documentation accordingly.

Tests

Tested with wrf NaN case.

Checklist for merging

• Updated changelog entry
• Documentation updated
• Version tag

Testing Datasets

• Dataset needed for testing available upon request
• Dataset download instructions included
• No dataset needed

[hkershaw-brown]

Great fix, thanks Benjamin.

I've been testing the fix on Cheyenne with several different compilers. (ifort, gfortran, nvfortran). One of the compilers (nvfortran) that people use on Cheyenne does not have an isnan function.

So let's replace isnan with ret_spvalR8 /= ret_spvalR8 to make the code work with all the Cheyenne compilers.

If you are interested, we have had some discussion of NaNs here #176
Once you have access to Cheyenne you will be able to try out the various compilers.

Cheers,
Helen