feat: add new indicators (Decay, Edecay, MinusDi, MinusDm, PlusDi, PlusDm, Maxindex, Minindex, Sarext) and update pine scripts, core libs, validation tests, and python bindings

lib/core/ringbuffer/RingBuffer.Tests.cs

@@ -12,7 +12,7 @@ public class RingBufferTests
         Assert.Equal(0, buffer.Count);
         Assert.False(buffer.IsFull);
         Assert.Equal(0, buffer.Sum);
-        Assert.Equal(0, buffer.Average);
+        Assert.True(double.IsNaN(buffer.Average));
     }
 
     [Fact]
@@ -192,7 +192,7 @@ public class RingBufferTests
 
         Assert.Equal(0, buffer.Count);
         Assert.Equal(0, buffer.Sum);
-        Assert.Equal(0, buffer.Average);
+        Assert.True(double.IsNaN(buffer.Average));
         Assert.False(buffer.IsFull);
     }
 
@@ -453,11 +453,11 @@ public class RingBufferTests
     }
 
     [Fact]
-    public void Average_EmptyBuffer_ReturnsZero()
+    public void Average_EmptyBuffer_ReturnsNaN()
     {
         var buffer = new RingBuffer(5);
 
-        Assert.Equal(0, buffer.Average);
+        Assert.True(double.IsNaN(buffer.Average));
     }
 
     [Fact]

lib/core/ringbuffer/RingBuffer.cs

@@ -141,12 +141,12 @@ public sealed class RingBuffer : IEnumerable<double>
 
     /// <summary>
     /// Average of all elements in the buffer.
-    /// Returns 0 if buffer is empty.
+    /// Returns <see langword="double.NaN"/> if buffer is empty.
     /// </summary>
     public double Average
     {
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        get => _count > 0 ? _sum / _count : 0;
+        get => _count > 0 ? _sum / _count : double.NaN;
     }
 
     /// <summary>

lib/core/simd/SimdExtensions.cs

@@ -90,7 +90,7 @@ public static class SimdExtensions
         for (int i = 0; i < span.Length; i++)
         {
             double diff = span[i] - mean;
-            sumSquares += diff * diff;
+            sumSquares = Math.FusedMultiplyAdd(diff, diff, sumSquares);
         }
         return sumSquares / (span.Length - 1);
     }
@@ -438,7 +438,7 @@ public static class SimdExtensions
             for (; i < span.Length; i++)
             {
                 double diff = span[i] - m;
-                result += diff * diff;
+                result = Math.FusedMultiplyAdd(diff, diff, result);
             }
 
             return result / (span.Length - 1);
@@ -682,17 +682,17 @@ public static class SimdExtensions
         // Unroll scalar loop with 4 accumulators to break dependency chains
         for (; i <= len - 4; i += 4)
         {
-            s1 += Unsafe.Add(ref ar, i) * Unsafe.Add(ref br, i);
-            s2 += Unsafe.Add(ref ar, i + 1) * Unsafe.Add(ref br, i + 1);
-            s3 += Unsafe.Add(ref ar, i + 2) * Unsafe.Add(ref br, i + 2);
-            s4 += Unsafe.Add(ref ar, i + 3) * Unsafe.Add(ref br, i + 3);
+            s1 = Math.FusedMultiplyAdd(Unsafe.Add(ref ar, i), Unsafe.Add(ref br, i), s1);
+            s2 = Math.FusedMultiplyAdd(Unsafe.Add(ref ar, i + 1), Unsafe.Add(ref br, i + 1), s2);
+            s3 = Math.FusedMultiplyAdd(Unsafe.Add(ref ar, i + 2), Unsafe.Add(ref br, i + 2), s3);
+            s4 = Math.FusedMultiplyAdd(Unsafe.Add(ref ar, i + 3), Unsafe.Add(ref br, i + 3), s4);
         }
 
         double s = s1 + s2 + s3 + s4;
 
         for (; i < len; i++)
         {
-            s += Unsafe.Add(ref ar, i) * Unsafe.Add(ref br, i);
+            s = Math.FusedMultiplyAdd(Unsafe.Add(ref ar, i), Unsafe.Add(ref br, i), s);
         }
         return s;
     }

lib/core/tseries/tseries.cs

@@ -213,6 +213,12 @@ public class TSeries : IReadOnlyList<TValue>, ITValuePublisher
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public void Add(DateTime time, double value, bool isNew = true) => Add(new TValue(time, value), isNew);
 
+    /// <remarks>
+    /// <b>Synthetic timestamps:</b> Each element receives a fabricated timestamp starting at
+    /// <see cref="DateTime.UtcNow"/> (captured once at call time) and incrementing by one minute
+    /// per item. These timestamps do not reflect real market time. Use the typed overloads
+    /// (<see cref="Add(TValue)"/>, <see cref="Add(DateTime,double,bool)"/>) when real timestamps matter.
+    /// </remarks>
     public void Add(IEnumerable<double> values)
     {
         long t = DateTime.UtcNow.Ticks;