Fix cross track point perturbation

[SorooshMani-NOAA]

Fixes #118

[SorooshMani-NOAA]

@WPringle I think the failed tests are due to wrong references. I'll do more testing on all the 3 storms from NHC, but can you check if you see anything wrong with the changes I made?

[WPringle]

@SorooshMani-NOAA Thanks for fix! Although it's strange since alpha already looks like it should be positive always and reason for not needing abs() value.

[SorooshMani-NOAA]

Although it's strange since alpha already looks like it should be positive

@WPringle I actually realized that later, but just wanted to be extra sure, the main fix was related to how 1 dim arrays where being incorrectly meaned or diffed

[WPringle]

Although it's strange since alpha already looks like it should be positive

@WPringle I actually realized that later, but just wanted to be extra sure, the main fix was related to how 1 dim arrays where being incorrectly meaned or diffed

oh right, gotcha. think everything looks good

[WPringle]

if things are fixed without adding abs() around alpha then maybe don't make this change as it makes you think this is the bug but it's actually the other lines..

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.

Project coverage is 21.29%. Comparing base (eede830) to head (5b7c4e4).
Report is 14 commits behind head on main.

Files	Patch %	Lines
ensembleperturbation/perturbation/atcf.py	0.00%	3 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #122   +/-   ##
=======================================
  Coverage   21.29%   21.29%           
=======================================
  Files          28       28           
  Lines        3762     3762           
=======================================
  Hits          801      801           
  Misses       2961     2961           

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