diff --git a/include/sim.h b/include/sim.h
index debdf0e..6bd397a 100644
--- a/include/sim.h
+++ b/include/sim.h
@@ -383,12 +383,11 @@ void write2CSV(outVector &stateVector, Vehicle &State) {
   outfile.close();
 }
 
-double derivative(double x2, double x1, double dt) {
-  double dxdt = (x2 - x1) / (dt / 1000);
+double derivative(double current, double previous, double step) {
+  double dxdt = (previous - current) / (step / 1000);
   return dxdt;
 }
 
-double integral(double x, double y, double dt) {
-  double integ = (x * dt / 1000) + y;
-  return integ;
+double integral(double currentChange, double prevValue, double dt) {
+  return (currentChange * dt / 1000) + prevValue;
 }