Average True Range – EFS

atr() Built-in Study Functions

The Average True Range study (ATR) is a measure of volatility. It was introduced by Welles Wilder in his book New Concepts in Technical Trading Systems and has since been used as a component of many indicators and trading systems. Wilder has found that the high ATR values often occur at market bottoms following a "panic" sell-off. Low ATR values are often found during extended sideways periods, such as those found at tops and after consolidation periods.

Syntax

atr( nLength [, sym() | inv() ][, nBarIndex ] )

Parameters

Parameter:	Description:	Default:
nLength	Required. Number of periods to use for calculation.	n/a
sym() or inv()	[Optional] Function of sym() or inv() to determine symbol/interval source for the study.	Chart's sym/inv
nBarIndex	[Optional] Bar index of series to retrieve .	n/a

Return Value(s)

Returns a Series Object when nBarIndex is not specified.

Returns a single value when nBarIndex is specified.

Notes

Only available in versions 7.9 or later.

Code Examples

Single Line Indicator:

function main() {
  return atr(14);
}

Retrieve single values:

function main() {
  var nValue_0 = atr(14, 0); // Current Bar Index
  var nValue_1 = atr(14, -1); // Prior Bar Index
  return new Array(nValue_0, nValue_1);
}

Initialize a Series Object:

var xStudy = null;
function main() {
if (xStudy == null) {
xStudy = atr(14);
} // retrieve single values for conditional statements
var nValue_0 = xStudy.getValue(0); // Current Bar Index value
var nValue_1 = xStudy.getValue(-1); // Prior Bar Index value
return nValue_0; // Plot Current Bar Index Value
}

Initialize a Series Object based on an external interval:

var xStudy = null;
var bInit = false; // Initialization flag
function main() {
  if (bInit == false) {
    xStudy = atr(14, inv(20)); // 20-min interval
    bInit = true;
  } // retrieve single values for conditional statements
  var nValue_0 = xStudy.getValue(0); // Current Bar Index value
  var nValue_1 = xStudy.getValue(-1); // Prior Bar Index value
  return getSeries(xStudy); // Synchronized Series plot
}

Initialize a Series Object based on an external symbol and interval:

var xStudy = null;
var bInit = false; // Initialization flag
function main() {
  if (bInit == false) {
    xStudy = atr(14, sym("IBM,20")); // IBM 20-min interval
    bInit = true;
  } // retrieve single values for conditional statements
  var nValue_0 = xStudy.getValue(0); // Current Bar Index value
  var nValue_1 = xStudy.getValue(-1); // Prior Bar Index value
  return getSeries(xStudy); // Synchronized Series plot
}