Fixed a couple of issues with GetLinearRegression().

cubiclesoft · cubiclesoft · commit 1dbd0f97e659 · 2020-08-19T17:29:27.000-07:00
diff --git a/chart/flex_forms_chart.php b/chart/flex_forms_chart.php
@@ -123,7 +123,7 @@ public static function FieldType(&$state, $num, &$field, $id)
 			}
 		}
 
-		function GetLinearRegression($xvals, $yvals, $calcpoints = true)
+		public static function GetLinearRegression($xvals, $yvals, $calcpoints = true)
 		{
 			// Calculate:  y = a + bx
 			// Where:
@@ -160,7 +160,8 @@ function GetLinearRegression($xvals, $yvals, $calcpoints = true)
 
 			$b = $Sxy / $Sxx;
 			$a = ($Ey - ($b * $Ex)) / $n;
-			$r = $Sxy / sqrt($Sxx * $Syy);
+			$r = sqrt($Sxx * $Syy);
+			$r = ($r == 0 ? 1 : $Sxy / $r);
 
 			if (!$calcpoints)  $points = false;
 			else

Original file line number	Diff line number	Diff line change
`@@ -123,7 +123,7 @@ public static function FieldType(&$state, $num, &$field, $id)`
`123`	`123`	`}`
`124`	`124`	`}`
`125`	`125`
`126`		`- function GetLinearRegression($xvals, $yvals, $calcpoints = true)`
	`126`	`+ public static function GetLinearRegression($xvals, $yvals, $calcpoints = true)`
`127`	`127`	`{`
`128`	`128`	`// Calculate: y = a + bx`
`129`	`129`	`// Where:`
`@@ -160,7 +160,8 @@ function GetLinearRegression($xvals, $yvals, $calcpoints = true)`
`160`	`160`
`161`	`161`	`$b = $Sxy / $Sxx;`
`162`	`162`	`$a = ($Ey - ($b * $Ex)) / $n;`
`163`		`- $r = $Sxy / sqrt($Sxx * $Syy);`
	`163`	`+ $r = sqrt($Sxx * $Syy);`
	`164`	`+ $r = ($r == 0 ? 1 : $Sxy / $r);`
`164`	`165`
`165`	`166`	`if (!$calcpoints) $points = false;`
`166`	`167`	`else`