/********************************************************************
 * Copyright Garth Doverspike  2001
 * frmGMom - Momentum per Bill Williams
 *
 * No warranty expressed or implied on functionality - Use at your own risk
 * If you find a bug please email me
********************************************************************/

function preMain() {
	setStudyTitle("GMOM");
	setCursorLabelName("GMOM");

	/*
	 * Set the properties of the default bar.  These will be the
	 * properties of any bar for which style, color, thickness is
	 * not specificed.
	 */
	setDefaultBarStyle(PS_SOLID);

/*
	setStudyMax(100);
	setStudyMin(-100);
*/

	setDefaultBarFgColor(Color.black);
	setDefaultBarThickness(2);
	
	
	setPlotType(PLOTTYPE_HISTOGRAM);
	
}

/*****
  Variables to remember across iterations to main.
****/

var vLastRet = 0;

/*
 * Momentum
 */
function main() {
  	
	var vhighs;
	var vlows;
	var vLookback = 34;
	var vShort = 5;
	var vSum;
	var vShortSum;
	var i;
	var vSymbol;
	

	/* 
	 * Get highs and lows for 34 bars
	 */
	
	vhighs = high (0, -vLookback);
	vlows = low (0, -vLookback);

	/*
     * Check for NULL returns
     */
	
    if (vhighs == null || vlows == null) {
         return;
    }
    
    if ((vSymbol = getSymbol()) == null){
        return;
    }
        
    /*
     * Calc the two MA's
     */
     vSum = 0;
     vShortSum = 0;
     for (i = 0; i < vLookback; i++) {
         vSum += (((vhighs[i] - vlows[i])/2) + vlows[i]);
         if (i == (vShort - 1)){
             vShortSum = vSum;
         }
     }

    vSum = vSum/vLookback;
    vShortSum = vShortSum/vShort;
    
    switch (vSymbol){
        case ("$INDU"):
            vSum = (vShortSum - vSum)/100;
            break;
        case ("$COMPQ"):
            vSum = (vShortSum - vSum)/10;
            break;
        default:
            vSum = (vShortSum - vSum); 
    }
     if (vSum < vLastRet){
         setBarFgColor(Color.red);
     } else {
         setBarFgColor(Color.green);
     }  
     
     vLastRet = vSum;
     
     return (vSum);   
}