Writing an SMA custom indicator in MQL4 without iMA()

Question

As an exercise to learn MQL4, I'm writing a custom indicator which just replicates the Simple Moving Average, but without using the builtin iMA() function. The code below paints the indicator onto the chart, but every part of the line except the ending is showing extremely low values. For instance, on the AUD/CAD chart, which is usually, in 0.80-0.90 range, the SMA line is around 0.20-0.30.

The line moves up and down in-sync with the price, and the very last bar seems to have an accurate reading ( as the SMA spikes towards the current price at that point ), but everything else is way low. I've exhausted every possible reason for why this may be happening, and nothing is changing it. Can somebody help me to figure out what is going wrong?

/*
   SELF-CODED 5-DAY SMA
   Set up buffer with style, indexbegin, and color
   for each bar:
       calculate closing price of last 4 bars and current price
       use to find SMA value at that bar
   update last value after every tick
   lock each bar's SMA value once the bar has close
*/
#property strict
#property indicator_chart_window
#property indicator_buffers 1

double buffer[];

int OnInit() 
   {
   IndicatorBuffers(1);
   SetIndexBuffer(0, buffer);
   SetIndexStyle(0, DRAW_LINE);

   return(INIT_SUCCEEDED);
   }

int OnCalculate( const int       rates_total,
                 const int       prev_calculated,
                 const datetime &time[],
                 const double   &open[],
                 const double   &high[],
                 const double   &low[],
                 const double   &close[],
                 const long     &tick_volume[],
                 const long     &volume[],
                 const int      &spread[]
                 )
   {
   int limit = rates_total - prev_calculated;

   buffer[0] = iClose(NULL, 0, 0); 

   for(int b = 1; b<5; b++)
      {
      buffer[0] = buffer[0] + iClose(NULL, 0, b);
      }
   buffer[0] = buffer[0]/5;   

   for(int i = 1; i<limit; i++)
      {
      buffer[i] = iClose(NULL, 0, i); // Placeholder in first for loop interation
      for(int a = 1; a<4; a++) {
         {
         buffer[i] = buffer[i] + iClose(NULL, 0, i+a);
         }
      buffer[i] = buffer[i]/5.0;
      }
   }
return(rates_total);   
}

The proposed algorithm is per-se very inefficient and will require a few changes in algorithmical thinking, but StackOverflow promotes MCVE policy to base all code-related subjects to a Complete and Verifiable ( i.e. reapeatable, incl. data-dependent values ) -- so kindly update your post as proposed above. Anyway, welcome to StackOverflow and Wild Worlds of MQL4 — user3666197
Would you mind posting a few quantitative outputs? Something alike this: Print( "SYMBOL:", _Symbol," PERIOD:", PERIOD_CURRENT, " Last 6 Bars Close[i] := [ ", Close[5], ", ", Close[4], ", ", Close[3], ", ", Close[2], ", ", Close[1], ", ", Close[0]," ], SmaToTEST[1] = ", iCustom( _Symbol, PERIOD_CURRENT, "SMA", 0, 1 ), "SmaToTEST[0] = ", iCustom( _Symbol, PERIOD_CURRENT, "SMA", 0, 0 ) ); ? — user3666197

Daniel Kniaz Daniel Kniaz · Accepted Answer · 2016-08-19T15:55:28

buffer[i] = iClose(NULL, 0, i);        // Placeholder in first for loop iteration
for ( int a = 1; a < 4; a++ ) {
    {
      buffer[i] = buffer[i] + iClose(NULL, 0, i+a);
      }
buffer[i] = buffer[i]/5.0;

this cannot be correct - ok if "i" is 1,
then
buffer[1] = (Close[1]+Close[1+1]+Close[1+2]+Close[1+3]) / 5,
as you sum from i+0 to i+3, 4 elements not five.

To fix : "a<=4".

it is advised to check number of previously calculated bars so that to update only recent ones, and start from Bars-1 (the earliest bar) and skip a little then calculate all the values in the way

sum       += Close[i]; 
Buffer[i]  = sum / 5; 
sum       -= Close[i+4];
i--;                      // inside a loop

Writing an SMA custom indicator in MQL4 without iMA()

2 Answers

Took a harder way ahead, once decided to write a `Custom Indicator` first

So, how to attack that?

Writing an SMA custom indicator in MQL4 without iMA()

2 Answers

Took a harder way ahead, once decided to write a Custom Indicator first

So, how to attack that?

Took a harder way ahead, once decided to write a `Custom Indicator` first