refactor: CalculateALMA

Indicators/MyIndicators/ALMA.mq5

@@ -5,12 +5,12 @@
 //+------------------------------------------------------------------+
 #property copyright "Copyright 2025, xxxxxxxx"
 #property link      ""
-#property version   "1.01" // Corrected MQL5 syntax for data handling
+#property version   "1.02" // Corrected calculation logic to match TradingView
 #property description "Arnaud Legoux Moving Average (ALMA)"
 
 //--- Indicator Window and Plot Properties ---
 #property indicator_chart_window
-#property indicator_buffers 1
+#property indicator_buffers 2 // ALMA and a buffer for the source price
 #property indicator_plots   1
 
 //--- Plot 1: ALMA line
@@ -28,7 +28,7 @@ input double             InpAlmaSigma    = 6.0;     // Sigma (smoothness)
 
 //--- Indicator Buffers ---
 double    BufferALMA[];
-double    price_buffer[]; // A buffer to store the source price data
+double    BufferPrice[]; // A buffer to store the source price data
 
 //--- Global Variables ---
 int       ExtAlmaPeriod;
@@ -49,16 +49,13 @@ void OnInit()
    ExtAlmaOffset = InpAlmaOffset;
    ExtAlmaSigma  = (InpAlmaSigma <= 0) ? 0.01 : InpAlmaSigma;
 
-//--- Map the buffer and set its properties
+//--- Map the buffers and set them as non-timeseries
-   SetIndexBuffer(0, BufferALMA, INDICATOR_DATA);
+   SetIndexBuffer(0, BufferALMA,  INDICATOR_DATA);
-   ArraySetAsSeries(BufferALMA, false);
+   SetIndexBuffer(1, BufferPrice, INDICATOR_CALCULATIONS);
+   ArraySetAsSeries(BufferALMA,  false);
+   ArraySetAsSeries(BufferPrice, false);
 
-// We also need to set our calculation buffer as a non-timeseries
+//--- Create a handle to get the source price data
-   SetIndexBuffer(1, price_buffer, INDICATOR_CALCULATIONS);
-   ArraySetAsSeries(price_buffer, false);
-
-//--- Create a handle to get the source price data ---
-// Using iMA with period 1 is a standard trick to get any APPLIED_PRICE series
    price_handle = iMA(_Symbol, _Period, 1, 0, MODE_SMA, InpAppliedPrice);
    if(price_handle == INVALID_HANDLE)
      {
@@ -89,8 +86,12 @@ int OnCalculate(const int rates_total,
    if(rates_total < ExtAlmaPeriod)
       return(0);
 
-//--- Copy the source price data into our buffer ---
+//--- Check if the source indicator is ready
-   if(CopyBuffer(price_handle, 0, 0, rates_total, price_buffer) != rates_total)
+   if(BarsCalculated(price_handle) < rates_total)
+      return(0);
+
+//--- Copy the source price data into our buffer
+   if(CopyBuffer(price_handle, 0, 0, rates_total, BufferPrice) != rates_total)
      {
       Print("Error copying source price data.");
       return(0);
@@ -99,15 +100,14 @@ int OnCalculate(const int rates_total,
 //--- Main calculation loop (full recalculation for stability)
    for(int i = ExtAlmaPeriod - 1; i < rates_total; i++)
      {
-      // Calculate ALMA for the current bar 'i' using the copied price data
+      BufferALMA[i] = CalculateALMA(i, BufferPrice);
-      BufferALMA[i] = CalculateALMA(i, price_buffer);
      }
 
    return(rates_total);
   }
 
 //+------------------------------------------------------------------+
-//| Calculates a single ALMA value for a given position.             |
+//| Calculates a single ALMA value for a given position. (CORRECTED) |
 //+------------------------------------------------------------------+
 double CalculateALMA(const int position, const double &price_array[])
   {
@@ -120,7 +120,13 @@ double CalculateALMA(const int position, const double &price_array[])
    for(int j = 0; j < ExtAlmaPeriod; j++)
      {
       double weight = MathExp(-1 * MathPow(j - m, 2) / (2 * s * s));
-      sum += price_array[position - ExtAlmaPeriod + 1 + j] * weight;
+
+      // --- FIX: Correct indexing to match Pine Script's logic ---
+      // This calculates the index of the bar within the sliding window,
+      // starting from the oldest to the newest.
+      int price_index = position - (ExtAlmaPeriod - 1) + j;
+
+      sum += price_array[price_index] * weight;
       norm += weight;
      }