Relative Strength EFS Question

[pointrunner]

I came across this relative strength efs: eSignal Bulletin Board » eSignal Formula Script (EFS) Central » EFS Library - Discussion Board » Spread / Overlays » RelativeStrengthRatio.efs.

It calculates the strength of a security relative to a different security, like $SPX.

I'm looking for something similar, but instead of comparing current prices of each security, I want to compare each security's change from prior day's close (on an intraday basis). For example, in comparing KO vs. PEP, I'd be looking to plot: ((Current Price of KO / Prior Day's Close of KO) / (Current Price of PEP / Prior Day's Close of PEP)).

Any help or advice would be greatly appreciated. I'm trying to learn to write my own scripts for the first time, and it's been a tough start.

Thanks,

John P.



/************************************************** **************************************************
Copyright © eSignal, a division of Interactive Data Corporation. 2003. All rights reserved.
This sample eSignal Formula Script (EFS) may be modified and saved under a new
filename; however, eSignal is no longer responsible for the functionality once modified.
eSignal reserves the right to modify and overwrite this EFS file with each new release.
************************************************** ************************************************** */

var vLoaded = false;
var vEdit = false;
var cSym = "";
var vSym = "$SPX";

function preMain() {
if (vLoaded == false) {
setDefaultBarFgColor(Color.blue);
} else {
if (vEdit == false) {
setStudyTitle(cSym + " vs. " + vSym + " ");
setCursorLabelName(cSym + "\/" + vSym);
} else {
setStudyTitle(cSym + " vs. ");
setCursorLabelName(cSym + "\/" + vSym);
}
}
}

function main(Symbol1) {
if (vLoaded == false) {
cSym = getSymbol();
if (Symbol1 == null) {
vSym = "$SPX";
vEdit = false
} else {
vSym = Symbol1;
vEdit = true;
}
vLoaded = true;
preMain();
}

if (vSym != null) {
var b = close(0, 1, vSym);
var vValue = close()/b;
return vValue;
} else {
return;
}
}