fix negative weights

[db091756]

PR Type

• Bugfix

Description

Ensures weights are greater than or equal to zero and sum to one. Fixes bug detailed in listed issue.

How Has This Been Tested?

All tests pass.

Does this PR introduce a breaking change?

(Write your answer here.)

Screenshots

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Checklist before requesting a review

• I have made sure that my PR is not a duplicate.
• My code follows the style guidelines of this project.
• I have commented my code, particularly in hard-to-understand areas.
• I have performed a self-review of my code.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.
• I have added tests that prove my fix is effective or that my feature works.
• New and existing unit tests pass locally with my changes.
• Any dependent changes have been merged and published in downstream modules.

[pc532627]

One small unittest request but otherwise looks good.