From 2ebdff41e7d185487dfcb40460a2116556e7789d Mon Sep 17 00:00:00 2001
From: Folkert Nobels <nobels@strw.leidenuniv.nl>
Date: Thu, 28 Feb 2019 10:04:50 +0100
Subject: [PATCH] Add documentation to the pearson correlation function
---
tests/testRandom.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/tests/testRandom.c b/tests/testRandom.c
index 44d4799719..2be7cf5fb2 100644
--- a/tests/testRandom.c
+++ b/tests/testRandom.c
@@ -26,6 +26,28 @@
/* Local headers. */
#include "swift.h"
+/**
+ * @brief Compute the Pearson correlation coefficient for two sets of numbers
+ *
+ * The pearson correlation coefficient between two sets of numbers can be
+ * calculated as:
+ *
+ * <x*y> - <x>*<y>
+ * r_xy = ----------------------
+ * (var(x) * var(y))^.5
+ *
+ * In the case that both sets are purely uncorrelated the value of the
+ * Pearson correlation function is expected to be close to 0. In the case that
+ * there is positive correlation r_xy > 0 and in the case of negative
+ * correlation, the function has r_xy < 0.
+ *
+ * @param mean1 average of first series of numbers
+ * @param mean2 average of second series of numbers
+ * @param total12 sum of x_i * y_i of both series of numbers
+ * @param var1 variance of the first series of numbers
+ * @param var2 variance of the second series of numbers
+ * @param number of elements in both series
+ * */
double pearsonfunc(double mean1, double mean2, double total12, double var1, double var2, int counter) {
const double mean12 = total12 / (double)counter;
--
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