Decorr diff variance array incorrect

[laldoroty]

When printing the median values of the input arrays and the output variance arrays, we get this for the Gaussian tests:

This is clearly wrong. 19 is way too small and 26855 is way too big.

Upon further inspection, the equation we are using was wrong (first is incorrect and current, second is correct):

[wmwv]

Is this Issue about the create_variance_image function here:

sfft/sfft/SpaceSFFTCupyFlow.py

Line 440 in ccf7a6c

def create_variance_image( self ):

[laldoroty]

Is this Issue about the create_variance_image function here:

sfft/sfft/SpaceSFFTCupyFlow.py

Line 440 in ccf7a6c
def create_variance_image( self ):

Yes.

[thomasvrussell]

@laldoroty I just pushed a fix for create_variance_image (see the latest branch 26-save-matching-kernel-for-diagnose-purpose), can you run the Gaussian test again to see if we can get reasonable variance?

[laldoroty]

Now we're printing (median values of the arrays):

PixA_targetVar_GPU 10000.0
PixA_resamp_objectVar_GPU 10000.0
self.target_skyrms 98.62380981445312
self.object_skyrms 98.61939239501953
PSF_resamp_object_GPU 3.5025537080543155e-20
PSF_target_GPU 7.903822782033761e-21
PixA_dDIFFVar_GPU 20000.94449101116

If I run the full "light curve", the output looks like this: