2 files changed, 6 insertions, 1 deletions
diff --git a/grapher/Models/Calculations/AccelCalculator.cs b/grapher/Models/Calculations/AccelCalculator.cs
index 8865939..ab6e9de 100644
--- a/grapher/Models/Calculations/AccelCalculator.cs
+++ b/grapher/Models/Calculations/AccelCalculator.cs
@@ -64,6 +64,11 @@ namespace grapher.Models.Calculations
 
             foreach (var magnitudeDatum in magnitudeData)
             {
+                if (magnitudeDatum.magnitude <=0)
+                {
+                    continue;
+                }
+
                 var output = accel.Accelerate(magnitudeDatum.x, magnitudeDatum.y, MeasurementTime);
                 var outMagnitude = Magnitude(output.Item1, output.Item2);
 
diff --git a/grapher/Models/Calculations/AccelChartData.cs b/grapher/Models/Calculations/AccelChartData.cs
index fbf1944..5225e08 100644
--- a/grapher/Models/Calculations/AccelChartData.cs
+++ b/grapher/Models/Calculations/AccelChartData.cs
@@ -54,7 +54,6 @@ namespace grapher.Models.Calculations
             {
                 var velIdx = GetVelocityIndex(outVelocityValue);
 
-                velIdx = Math.Min(velIdx, VelocityPoints.Count - 1);
                 values = (VelocityPoints.ElementAt(velIdx).Key, AccelPoints.ElementAt(velIdx).Value, GainPoints.ElementAt(velIdx).Value);
                 OutVelocityToPoints.Add(outVelocityValue, values);
                 return values;
@@ -81,6 +80,7 @@ namespace grapher.Models.Calculations
             }
 
             velIdx = Math.Min(velIdx, VelocityPoints.Count - 1);
+            velIdx = Math.Max(velIdx, 0);
 
             return velIdx;
         }