Correct way to calculate an indicator in a for loop

Hi everyone,

I wish to know if this is the correct way to calculate indicator's value in a for loop (throughout all the available bars):

int OnCalculate(...)

{

//... 

ArraySetAsSeries(SignalLine,false); 

//... 

for(int i=0; i<Bars; i++)

{ 

   double ma=iMA(NULL,0,MaPeriod,0,MaMethod,MaPrice,i);

//...

SignalLine[i]=ma;

}

//...

} 

return rates_total

} 

P.S. Logically in this simple case I would like to represent and plot a MA replication by iMA object. But I am not sure of how I set the loop. I get a bit of difference compared to the one calculated with built-in MT4. I cannot figure out why!

Thanks