Tighten power-trace bound of odd loop Hafnian

[GregoryMorse]

Context:: The loop Hafnian for odd sized matrices contains an excessive bound, making it a code readability issue and efficiency issue.

Description of the Change: In the inner-loop, powtrace[i // 2] reaches a maximum at n == i according to the loop range, hence the power-trace need not compute any additional power traces.

Benefits: Readability and efficiency.

Possible Drawbacks:

Related GitHub Issues:

[codecov[bot]]

Codecov Report

Merging #362 (73c3fa0) into master (01fb78c) will not change coverage. The diff coverage is n/a.

Additional details and impacted files

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[nquesada]

Pending this passing the unit tests, it has my approval.

[nquesada]

@GregoryMorse Could you update the CHANGELOG?

[GregoryMorse]

@GregoryMorse Could you update the CHANGELOG?

All set. Was looking into if a more unified treatment of the odd-sized loop Hafnians was possible, but only noticed this small improvement thus far.