Various sign/indexing fixes and performance improvements#2

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skilledwolf merged 28 commits intomainfrom

Dec 3, 2025

Commits on Nov 30, 2025

- made changes that agree with the Julia version (analytic Exchange matrix elements) up to flipping b field sign (complex conjugate and a sign).
SparshMishra97
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Did checks and compared Julia implementation results to revised package results
SparshMishra97
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added additional comments
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Commits on Dec 3, 2025