Re: Sv: understanding easylanguage code

[Bob Fulks <bfulks@xxxxxxxxxxxx>]

You are making this much harder than it is. The code is:

   If CurrentBar <= 1 Then Begin
      Factor = 2 / (Length + 1);
      XAverage = Price;
   End Else
      XAverage = Factor * Price + (1 - Factor) *  XAverage[1];

So on the first bar of data (CurrentBar = 1) it calculates "Factor" and sets XAverage to the "Price" input to initialize it.

Then on the next bar it calculates a new value for XAverage:

      XAverage = Factor * Price + (1 - Factor) *  XAverage[1];

using the value of XAverage from the previous bar ("XAverage[1]")

Then on the next bar it calculates a new value for XAverage:

      XAverage = Factor * Price + (1 - Factor) *  XAverage[1];

using the value of XAverage from the previous bar ("XAverage[1]")

etc., until it finished the calculation for the last bar on the chart.

Each value depends upon the previous value and only the previous value. But that value includes a component from all past values, obviously.

This is one of a class of digital filters called "Infinite Impulse Response" (IIR) filters where the current value depends upon all previous values back in time.

Do a Google search of "IIR Digital Filter" (14,000 hits as of today) to learn more that you ever wanted to know on these kinds of filters.

Bob Fulks