code reviews

lib/numerics/change/Change.Quantower.cs

@@ -23,6 +23,11 @@ public class ChangeIndicator : Indicator, IWatchlistIndicator
     private Change? _change;
     private Func<IHistoryItem, double>? _selector;
 
+    // Cached markers to avoid per-update allocations
+    private static readonly IndicatorLineMarker GreenMarker = new(Color.Green);
+    private static readonly IndicatorLineMarker RedMarker = new(Color.Red);
+    private static readonly IndicatorLineMarker GrayMarker = new(Color.Gray);
+
     public int MinHistoryDepths => Period + 1;
     public override string ShortName => $"CHANGE({Period})";
 
@@ -55,21 +60,25 @@ public class ChangeIndicator : Indicator, IWatchlistIndicator
         _change.Update(input, isNew);
 
         bool isHot = _change.IsHot;
+        double changeValue = _change.Last.Value;  // Cache to avoid repeated property access
 
-        LinesSeries[0].SetValue(_change.Last.Value, isHot, ShowColdValues);
+        LinesSeries[0].SetValue(changeValue, isHot, ShowColdValues);
         LinesSeries[1].SetValue(0);
 
         if (isHot || ShowColdValues)
         {
-            double change = _change.Last.Value;
-            Color color;
-            if (change > 0)
-                color = Color.Green;
-            else if (change < 0)
-                color = Color.Red;
-            else
-                color = Color.Gray;
-            LinesSeries[0].SetMarker(0, new IndicatorLineMarker(color));
+            // Use cached markers to avoid per-update allocations
+            IndicatorLineMarker marker = GetMarker(changeValue);
+            LinesSeries[0].SetMarker(0, marker);
         }
     }
+
+    [System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]
+    private static IndicatorLineMarker GetMarker(double value)
+    {
+        if (!double.IsFinite(value)) return GrayMarker;
+        if (value > 0) return GreenMarker;
+        if (value < 0) return RedMarker;
+        return GrayMarker;
+    }
 }

lib/numerics/change/Change.Tests.cs

@@ -162,10 +162,16 @@ public class ChangeTests
             indicator.Update(_source[i]);
         }
 
-        // Compare last 10 values
+        // Compare last 10 values between batch and streaming
+        var streamResult = new TSeries();
+        for (int j = 0; j < _source.Count; j++)
+        {
+            streamResult.Add(indicator.Update(_source[j]), true);
+        }
+
         for (int i = Math.Max(0, _source.Count - 10); i < _source.Count; i++)
         {
-            Assert.Equal(batchResult[i].Value, batchResult[i].Value, 1e-10);
+            Assert.Equal(batchResult[i].Value, streamResult[i].Value, 1e-10);
         }
 
         // Ensure final values match
@@ -214,4 +220,4 @@ public class ChangeTests
         Assert.True(change.IsHot);
         Assert.NotEqual(0.0, change.Last.Value);
     }
-}
+}