Need help modifying Fisher.efs

[muecke]

Need help again, because I simply do not understand the logic behind that language.

Inthe following efs it is mentioned that:

"you can create a nearly Gaussian probability density function by normalizing price
(or an indicator such as RSI) and applying the Fisher Transform."


So if I want to do that for example with the RSI, how would I need to modify the following original Fisher.efs?

addBand(1.5, PS_SOLID, 2, Color.red, "1.5");
addBand(1.38, PS_DASH, 1, Color.white, "1.38");
addBand(1.25, PS_DASH, 1, Color.white, "1.25");
addBand(1, PS_DASH, 1, Color.black, "1");
addBand(.75, PS_DASH, 1, Color.yellow, ".75");
addBand(.5, PS_DASH, 1, Color.white, ".5");
addBand(0, PS_SOLID, 2, Color.green, "0");
addBand(-.5, PS_DASH, 1, Color.white, "-.5");
addBand(-.75, PS_DASH, 1, Color.yellow, "-.75");
addBand(-1, PS_DASH, 1, Color.black, "-1");
addBand(-1.25, PS_DASH, 1, Color.white, "-1.25");
addBand(-1.38, PS_DASH, 1, Color.white, "-1.38");
addBand(-1.5, PS_SOLID, 2, Color.red, "-1.5");


function preMain(){
    setStudyTitle("Ehlers");
    setCursorLabelName("Fisher", 0);
    setCursorLabelName("Trigger", 1);
    setDefaultBarFgColor(Color.red, 0);
    setDefaultBarFgColor(Color.black, 1);
    
    var fp01 = new FunctionParameter("Len", FunctionParameter.NUMBER);
    fp01.setName("Length");
    fp01.setLowerLimit(5);
    fp01.setDefault(9);
    
}
var Fish = 0;
var Fish_1 = 0;
var Value1 = 0;
var Value1_1 = 0;


function main(Len) {
    if (Len == null) 
        Len = 9;

    if(getBarState() == BARSTATE_NEWBAR) {
        
        Fish_1 = Fish;
        Value1_1 = Value1;
    }

    var Price = (high() + low()) / 2;
    var Pricei= (high() + low()) / 2;//added this variable
    var MaxH = 0;
    var MinL = 0;
    var i;
    setBarThickness(2,0); 
    setBarThickness(2,1); 
    for(i = 0; i < Len; i++) {
        Pricei = (high(-i) + low(-i)) / 2; //added this line 
        if(i == 0){
            MaxH = Pricei;//changed from: MaxH = high()
            MinL = Pricei;//changed from: MaxH = low()
        }
        else{
            MaxH = Math.max(MaxH, Pricei);//changed from: MaxH = Math.max(MaxH, high(-i))
            MinL = Math.min(MinL, Pricei);//changed from: MinL = Math.min(MinL, low(-i))
        }
    }

    var num1 = (MaxH - MinL);
    if (num1 <.001)
        num1 = .001;
    Value1 = .33 * 2 * ((Price - MinL) / (num1) - .5) + .67 * Value1_1;

    if(Value1 > .99)
        Value1 = .999;
    if(Value1 < -.99)
        Value1 = -.999;
    var num2 = (1 - Value1);
    if (num2 <.001)
        num2 = .001;
    Fish = .5 * Math.log((1 + Value1) / num2) + .5 * Fish_1;
    
    
    return new Array(Fish,Fish_1);//removed the redundant temp variable, use Fish_1 instead
} 

Alexis, I know you will help me out, like so many other times.
Think, it's about time for a bottle of champagne.............

thank you

[Guest]

Hi muecke,

I am not Alex, but I figured I could at least point you in the direction of an easier solution using efs2. Please check this fisher efs at the following link.

FWIW, when posting code, you should post the headers associated with the original efs. That is a courtesy extended to the author of the efs, in addition to making it easier to determine changes made to the original.

What you could do is pass the RSI to the efsInternal function. You can set that up using the EFS2 Toolbox in the EFS editor.

As far as understanding the logic behind the language, the JavaScript references in the Knowledgebase are an excellent place to start. Another method that has been helpful to me is use of the EFS2 Toolbox.