From 71ba720dc1b4034ffa80bc92ba6d268cee61291e Mon Sep 17 00:00:00 2001
From: Ahmet Inan <inan@aicodix.de>
Date: Sat, 18 Aug 2018 10:25:19 +0200
Subject: [PATCH] calculate and store intersections and slope

---
 regression.hh | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/regression.hh b/regression.hh
index 208c02a..e692e66 100644
--- a/regression.hh
+++ b/regression.hh
@@ -12,37 +12,41 @@ namespace DSP {
 template <typename TYPE>
 class SimpleLinearRegression
 {
-	TYPE avgX, avgY;
-	TYPE varX, covXY;
+	TYPE xint_, yint_, slope_;
 public:
-	SimpleLinearRegression(TYPE *x, TYPE *y, int LEN) : avgX(0), avgY(0), varX(0), covXY(0)
+	SimpleLinearRegression(TYPE *x, TYPE *y, int LEN)
 	{
+		TYPE avgX(0), avgY(0);
 		for (int i = 0; i < LEN; ++i) {
 			avgX += x[i];
 			avgY += y[i];
 		}
 		avgX /= LEN;
 		avgY /= LEN;
+		TYPE varX(0), covXY(0);
 		for (int i = 0; i < LEN; ++i) {
 			varX += (x[i] - avgX) * (x[i] - avgX);
 			covXY += (x[i] - avgX) * (y[i] - avgY);
 		}
+		xint_ = avgX - avgY * varX / covXY;
+		slope_ = covXY / varX;
+		yint_ = avgY - slope_ * avgX;
 	}
 	TYPE xint()
 	{
-		return avgX - avgY * varX / covXY;
+		return xint_;
 	}
 	TYPE slope()
 	{
-		return covXY / varX;
+		return slope_;
 	}
 	TYPE yint()
 	{
-		return avgY - slope() * avgX;
+		return yint_;
 	}
 	TYPE operator () (TYPE x)
 	{
-		return yint() + slope() * x;
+		return yint_ + slope_ * x;
 	}
 };