Refactor MAMA and HTIT implementation for improved accuracy and performance

lib/trends/sma/Sma.ZeroDiv.Tests.cs

@@ -0,0 +1,36 @@
+using System;
+using Xunit;
+using QuanTAlib;
+
+namespace QuanTAlib.Tests;
+
+public class SmaZeroDivTests
+{
+    [Fact]
+    public void Sma_Update_WithIsNewFalse_OnEmptyBuffer_DoesNotThrow()
+    {
+        var sma = new Sma(10);
+        
+        // Buffer is empty initially.
+        // Calling Update with isNew=false should not cause division by zero.
+        // It should return NaN or 0 or Last, but definitely not throw or return Infinity.
+        
+        var result = sma.Update(new TValue(DateTime.UtcNow, 100), isNew: false);
+        
+        // Since buffer count is 0, we expect NaN based on our fix.
+        Assert.True(double.IsNaN(result.Value), $"Expected NaN but got {result.Value}");
+    }
+
+    [Fact]
+    public void Sma_Update_WithIsNewFalse_AfterReset_DoesNotThrow()
+    {
+        var sma = new Sma(10);
+        sma.Update(new TValue(DateTime.UtcNow, 100));
+        sma.Reset();
+        
+        // Buffer is empty after Reset.
+        var result = sma.Update(new TValue(DateTime.UtcNow, 200), isNew: false);
+        
+        Assert.True(double.IsNaN(result.Value), $"Expected NaN but got {result.Value}");
+    }
+}

lib/trends/sma/Sma.cs

@@ -196,7 +196,7 @@ public sealed class Sma : AbstractBase
             _buffer.UpdateNewest(val);
         }
 
-        double result = _state.Sum / _buffer.Count;
+        double result = _buffer.Count > 0 ? _state.Sum / _buffer.Count : double.NaN;
         Last = new TValue(input.Time, result);
         PubEvent(Last);
         return Last;