Diff: Heater.cpp

Revision:

45:5f588512529b

Parent:

44:e358867319f6

Child:

46:47c394467c66

--- a/Heater.cpp	Fri Nov 15 15:59:32 2019 +0000
+++ b/Heater.cpp	Sat Nov 16 06:05:55 2019 +0000
@@ -21,6 +21,7 @@
     //Initialise values for averaging resistance
     n_acc = 0;
     R_acc = 0;
+    R2_acc = 0;
 }
 
 void Heater::read()
@@ -51,8 +52,9 @@
         R = cal_a + cal_b*R;  //Convert to Ohms
     }
     
-    // Calcualate accumulated resistance values for R_avg output
+    // Calculate accumulated resistance values for R_avg and R_var output
     R_acc = R_acc + R;
+    R2_acc = R2_acc + R*R
     n_acc ++;
         
 }
@@ -113,11 +115,18 @@
 float Heater::Get_R_avg()
 {
     R_avg = R_acc / (float) n_acc;
+    R_var = (R2_acc*R2_acc - R_avg*R_avg) / n_acc
     R_acc = 0;
+    R2_acc = 0;
     n_acc = 0;
     return R_avg;
 }
 
+float Heater::Get_R_var() // need to call Get_R_avg to calculate R_var before calling this function
+{
+    return R_var;
+}
+
 float Heater::Get_R_ref() const
 {
     return R_ref;