/*****************************************************************Provided By : eSignal. (c) Copyright 2003*****************************************************************/function preMain() { setPriceStudy(true); setStudyTitle("Bollinger Bands (EMA of Basis Line)"); setCursorLabelName("Upper Band", 0); setCursorLabelName("EMA Basis", 1); setCursorLabelName("Lower Band", 2); setDefaultBarFgColor(Color.blue, 0); // upper band setDefaultBarFgColor(Color.red, 1); // basis line setDefaultBarFgColor(Color.blue, 2); // lower band}var vEMA = null;var vEMA1 = null;var dPercent = 0.0;var bPrimed = false;function EMA(nLength, nClose) { var nBarState = getBarState(); var dSum = 0.0; var dRef; if(nBarState == BARSTATE_ALLBARS || bPrimed == false) { dPercent = (2.0 / (nLength + 1.0)); bPrimed = false; } if (nBarState == BARSTATE_NEWBAR) { vEMA1 = vEMA; } if(bPrimed == false) { for(i = 0; i < nLength; i++) { dSum += nClose[i]; } bPrimed = true; return (dSum / nLength); } else { return (((close() - vEMA1) * dPercent) + vEMA1); }}function main(nLength, nStdDev) { if(nLength == null || nLength <= 0) nLength = 20; if(nStdDev == null) nStdDev = 2; var vClose = getValue("Close", 0, -nLength); if(vClose == null) return; var sumX = 0; var sumX2 = 0; for (i = 0; i < nLength; ++i) { sumX += vClose[i]; sumX2 += (vClose[i] * vClose[i]) } var meanX = (sumX/nLength); var StdDev = Math.sqrt((sumX2/nLength) - (meanX*meanX)); vEMA = EMA(nLength, vClose); var vUpper = vEMA + (nStdDev * StdDev); var vBasis = vEMA; var vLower = vEMA - (nStdDev * StdDev); return new Array(vUpper, vBasis, vLower);} |
