From 04725cb1eff561d0d8547020b1d2ab3ff51fc990 Mon Sep 17 00:00:00 2001
From: Bryant Mairs <bwmairs@ucsc.edu>
Date: Thu, 12 Apr 2012 23:24:44 -0700
Subject: [PATCH] Fixed a stack overflow bug when using the regression fitting
 command in logfile plot. Solution involved just allocating on the heap
 instead of the stack.

---
 src/ui/QGCDataPlot2D.cc | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/src/ui/QGCDataPlot2D.cc b/src/ui/QGCDataPlot2D.cc
index 94d6426c3..d23a56d4e 100644
--- a/src/ui/QGCDataPlot2D.cc
+++ b/src/ui/QGCDataPlot2D.cc
@@ -561,7 +561,10 @@ void QGCDataPlot2D::loadCsvLog(QString file, QString xAxisName, QString yAxisFil
 bool QGCDataPlot2D::calculateRegression()
 {
     // TODO Add support for quadratic / cubic curve fitting
-    return calculateRegression(ui->xRegressionComboBox->currentText(), ui->yRegressionComboBox->currentText(), "linear");
+	qDebug() << ui->xRegressionComboBox->currentText();
+	qDebug() << ui->yRegressionComboBox->currentText();
+    //return false;
+	return calculateRegression(ui->xRegressionComboBox->currentText(), ui->yRegressionComboBox->currentText(), "quadratic");
 }
 
 /**
@@ -579,9 +582,15 @@ bool QGCDataPlot2D::calculateRegression(QString xName, QString yName, QString me
             ui->xRegressionComboBox->setCurrentIndex(curveNames.indexOf(xName));
             ui->yRegressionComboBox->setCurrentIndex(curveNames.indexOf(yName));
         }
+
+		// Create a couple of arrays for us to use to temporarily store some of the data from the plot.
+		// These arrays are allocated on the heap as they are far too big to go in the stack and will
+		// cause an overflow.
+		// TODO: Look into if this would be better done by having a getter return const double pointers instead
+		// of using memcpy().
         const int size = 100000;
-        double x[size];
-        double y[size];
+		double *x = new double[size];
+		double *y = new double[size];
         int copied = plot->data(yName, x, y, size);
 
         if (method == "linear") {
@@ -604,14 +613,12 @@ bool QGCDataPlot2D::calculateRegression(QString xName, QString yName, QString me
                 function = tr("Linear regression failed. (Limit: %1 data points. Try with less)").arg(size);
                 result = false;
             }
-        } else if (method == "quadratic") {
-
-        } else if (method == "cubic") {
-
         } else {
             function = tr("Regression method %1 not found").arg(method);
             result = false;
         }
+
+		delete x, y;
     } else {
         // xName == yName
         function = tr("Please select different X and Y dimensions, not %1 = %2").arg(xName, yName);
@@ -635,7 +642,7 @@ bool QGCDataPlot2D::calculateRegression(QString xName, QString yName, QString me
  *          the match of the regression.
  * @return 1 on success, 0 on failure (e.g. because of infinite slope)
  */
-int QGCDataPlot2D::linearRegression(double* x,double* y,int n,double* a,double* b,double* r)
+int QGCDataPlot2D::linearRegression(double *x, double *y, int n, double *a, double *b, double *r)
 {
     int i;
     double sumx=0,sumy=0,sumx2=0,sumy2=0,sumxy=0;
-- 
2.22.0