NIKX-Tech/numx

stats: Pearson correlation coefficient

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#81 opened on Jul 11, 2026

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enhancementgood first issue

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Description

Add numx_stats_correlation (Pearson's r) to the stats module, operating on two equal-length arrays.

Follow CONTRIBUTING.md exactly: full Doxygen header, NULL-checks, numx_status_t return, all four deliverables (header, impl, test, docs page). Use Kahan (compensated) summation for the accumulation, matching the pattern already used in numx_vec_dot (src/linalg.c) after #57.

Contributor guide

Research direction
Read the existing stats module implementation and the Kahan summation example in src/linalg.c. Follow the CONTRIBUTING.md guidelines to add the new function.
Tech stack
c
Domain
backend
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
CGit
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
80