Fisher Transform and ROC

[ianwaugh@xxxxxxxxx (Ian Waugh)]

In the November 2002 issue of TASC, Ehler discusses the Fisher Transform 
function which is a fairly simple piece of code:

Inputs:	Price((H+L)/2),Len(10);
Vars:	MaxH(0),	MinL(0),Fish(0);

MaxH = Highest(Price, Len);
MinL = Lowest(Price, Len);
if (MaxH - MinL)<>0 then Value1 = .33*2*((Price - MinL)/(MaxH - MinL) - 
.5) + .67*Value1[1];
If Value1 > .99 then Value1 = .999;
If Value1 < -.99 then Value1 = -.999;
Fish = .5*Log((1 + Value1)/(1 - Value1)) + .5*Fish[1];

Plot1(Fish, "Fisher");
Plot2(Fish[1], "Trigger");
Plot3(0,"0");


He also talks about another plot: "I multiplied the rate of change of 
the Fisher Transform by 10 and plotted this amplified rate of change 
over the Fisher transform." The crossings show turning points.

However, I have not been able to duplicate the ROC plot correctly. In 
Trader's Tips, the MetaStock code is simply given as:

10*ROC(fish,1,$)

I've tried a few variations including:

Plot4(10*RateOfChange(fish, 1));

but they simply create spikes consisting of very large numbers.

Can anyone please show me how to do it?

Ian