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That's explains two things:
1. What was going wrong.
2. Why I'm not a programmer.
Many thanks, Gary...
Ian
> > diff=c-c[1];
> > diff=average(diff,3);
> > plot1(diff1,"diff");
> >
> > Someone said the problem happens because "diff" has already been
> > used. I was trying to be thrifty (:-). However, I thought you were
> > allowed to change the value of a variable by referencing itself such
> > as:
> > count=count+1;
> >
> > So I assumed my version would work. Is there some obtuse aspect of
> > EL at work here?
>
> No, just a programming error.
>
> The average function calculates the average of the value of diff
> on the last 3 bars. You want the 3-bar average of c-c[1]. But
> what is the value of "diff" for the last 3 bars? On the current
> bar, it's c-c[1]. But on the previous two bars, it's NOT c-c[1],
> but the average you calculated on those bars!
>
> So instead of calculating the average of (c-c[1]), (c-c[1])[1],
> and (c-c[1])[2], which is what you wanted, you were calculating
> the average value of (c-c[1]), average(diff,3)[1], and
> average(diff,3)[2].
>
> When you added in the additional diff1 variable, you no longer
> overwrote diff with the average, so diff still contained the
> difference of c-c[1], and the average of diff was correct.
>
> If you want to use two separate vars like that, I suggest you
> change diff1 to avgdiff or something like that so it's clear what
> it is.
>
> diff=c-c[1];
> avgdiff=average(diff,3);
> plot1(avgdiff,"avgdiff");
>
> Gary
>
>
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