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One comment in relation to calling the function in a loop with the RSI
calculation outside the function. As the function ensures the two
consecutive close values aren't exactly the same, and this must be
done before the RSI calculation is performed, the Close array would
need to be scanned and all consecutive close values that are the same
changed before calling the RSI function and subsequently the loop.
GP
--- In amibroker@xxxxxxxxxxxxxxx, "gp_sydney" <gp.investment@xxx> wrote:
>
> Are you saying you want the Close value at every bar that would make
> the RSI 25% (or whatever) on that bar?
>
> You could do that in a loop by calling this function for every bar,
> but it might be a bit slow (make the RSI array calculation external,
> so that it's not repeated at every bar). Alternatively calculate the
> whole RSI array yourself in a loop, using the last part of the
> function to calculate the required closes at each bar (that would save
> having to calculate the average gain and loss at every bar, since
> those values would be tracked in variables from the first bar).
>
> Try just calling the function in a loop first, after making the RSI
> array calculation external, and see if that's fast enough (to make the
> RSI calculation external, move the statement "rsiArr = RSI(period);"
> back into the main code and make the variable "rsiArr" global).
> Iterate the loop from period+1 to BarCount-1.
>
> One small thing in that function too is that the statement "rval = 0"
> should be the very first statement, before the "if" statement.
>
> Regards,
> GP
>
>
> --- In amibroker@xxxxxxxxxxxxxxx, Amon Ra <amon_gizeh@> wrote:
> >
> > The function is good. Thanks a lot. I add another code line for
> plotting:
> > Plot(nextClose,"Predicted Close",colorBlack,styleOwnScale);
> > The result is just a line with one value: the last nextClose. Can it
> be plot a chart with all values for all data?
> >
> > gp_sydney <gp.investment@> wrote: The
> maths is a bit involved to show you how to calculate it, but
> > here's a function that does the job:
> >
> > Function NextRSI(bar, period, nextClose, nrsi)
> > {
> > if (bar >= period+1) {
> > clb = Close[bar];
> > if (clb == Close[bar-1])
> > Close[bar] = Close[bar] + 0.0001; // To avoid "0/0" term
> > rsiArr = RSI(period);
> > rval = 0;
> > rs = 100 / (100 - rsiArr[bar]) - 1;
> > rsp = 100 / (100 - rsiArr[bar-1]) - 1;
> > cgn = Close[bar] - Close[bar-1];
> > cls = -cgn;
> > if (cgn < 0)
> > cgn = 0;
> > if (cls < 0)
> > cls = 0;
> > alp = 0;
> > if (rsp - rs)
> > alp = (cls * rs - cgn) / ((period-1)*(rsp - rs));
> > agp = rsp * alp;
> > als = (alp * (period-1) + cls) / period;
> > agn = (agp * (period-1) + cgn) / period;
> > if (nextClose >= 0) {
> > cgn = nextClose - Close[bar];
> > cls = -cgn;
> > if (cgn < 0)
> > cgn = 0;
> > if (cls < 0)
> > cls = 0;
> > rsx = (agn * (period-1) + cgn) / (als * (period-1) +
cls);
> > rval = 100 - (100 / (1+rsx));
> > }
> > else {
> > rsn = 100 / (100 - nrsi) - 1;
> > if (nrsi < rsiArr[bar])
> > rval = Close[bar] - (agn * (period-1)) / rsn + als *
> > (period-1);
> > else
> > rval = Close[bar] + als * (period-1) * rsn - agn *
> > (period-1);
> > }
> > Close[bar] = clb; // Restore close array
> > }
> > return rval;
> > }
> >
> > In this function, "bar" is the index of the bar before the one you
> > want to calculate (BarCount-1 to calculate for tomorrow's bar),
> > "period" is the RSI period, "nextClose" is either the next close
value
> > if you want to work out the next RSI value for that close or -1
if you
> > want to solve for the next close, and "nrsi" is anything to calculate
> > the next RSI or the desired RSI value to calculate the next close to
> > give that RSI. Note that it will only work when "bar" is at least the
> > period plus two bars.
> >
> > As an example, to calculate tomorrow's close to give an RSI(14)
of 25%:
> >
> > nextClose = NextRSI(BarCount-1, 14, -1, 25);
> >
> > or to calculate tomorrow's RSI for a close of $1.20:
> >
> > nrsi = NextRSI(BarCount-1, 14, 1.20, -1);
> >
> > Note that the function needs a change in the close to calculate the
> > average loss and gain figures needed to iterate forward. If the close
> > at "bar" is the same as the close at "bar-1" then it's impossible to
> > calculate those averages, so the function modifies the Close[bar]
> > value fractionally to avoid the problem (the difference is not
usually
> > noticeable).
> >
> > Regards,
> > GP
> >
> > --- In amibroker@xxxxxxxxxxxxxxx, "amon_gizeh" <amon_gizeh@> wrote:
> > >
> > > Hello.
> > > I try to calculate what value for tommorow Close will make a
> crossover
> > > with line 25 (oversold level) or line 75 (overbought level). Can
> > > somebody help me?
> > > Thanks.
> > >
> >
>
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