fix: correct undefined variable typo in AWK scripts

[shiavm006]

Description

What is the purpose of this pull request?

This pull request:

• fixes a bug in tools/awk/variance.awk and tools/awk/stdev.awk where an undefined variable mu was used instead of the correctly initialized variable mean

Related Issues

Does this pull request have any related issues?

This pull request has the following related issues:

• None

Questions

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No.

Other

Any other information relevant to this pull request? This may include screenshots, references, and/or implementation notes.

Both scripts implement Welford's method for computing variance/standard deviation. The variable mean is properly initialized and updated during iteration, but line 44 incorrectly referenced mu, which is never defined. AWK treats undefined variables as 0, causing incorrect calculations.

Checklist

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• Read, understood, and followed the contributing guidelines.

AI Assistance

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• Yes
• No

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