# Directional Movement (ADX-DM)

ICE Data Services -

adx(), pdi(), ndi() Built-in Study Functions

Directional Movement (ADX-DM) indicates the strength of the overall trend. Typically, readings below 20-25 indicate a weak trend. +DI and -DI show the strength of the up trend (+DI) and the strength of the downtrend (-DI), respectively.

Syntax

adx( nLength , nSmoothing [, sym() | inv() ][, nBarIndex ] )
pdi( nLength , nSmoothing [, sym() | inv() ][, nBarIndex ] )
ndi ( nLength , nSmoothing [, sym() | inv() ][, nBarIndex ] )

Parameters

 Parameter: Description: Default: nLength Required. Number of periods to use for calculation. n/a nSmoothing Required. Number of periods to use for calculation. n/a sym() orinv() [Optional]  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.

These built-in study functions do not accept other series objects as the source for the study other than sym() or inv().

Code Examples

Single Line Indicator:
```function main() {
return new Array(adx(14, 14), pdi(14, 14), ndi(14, 14));
}```

Single Line Study-on-Study Indicator:
`N/A See notes.`

Retrieve single values:

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

Initialize Series Objects:
```//global Series Object variables
var xStudy1 = null;
var xStudy2 = null;
var xStudy3 = null;
function main() {
if (xStudy1 == null) xStudy1 = adx(14, 14);
if (xStudy2 == null) xStudy2 = pdi(14, 14);
if (xStudy3 == null) xStudy3 = ndi(14, 14); // retrieve single values for conditional statements
var nValue1_0 = xStudy1.getValue(0); // Current Bar Index value
var nValue2_0 = xStudy2.getValue(0); // Current Bar Index value
var nValue3_0 = xStudy3.getValue(0); // Current Bar Index value
var nValue1_1 = xStudy1.getValue(-1); // Prior Bar Index value
// Plot Current Bar Index Value
return new Array(nValue1_0, nValue2_0, nValue3_0);
}```

Initialize a Series Object based on an external interval:
```// global Series Object variables
var xStudy1 = null;
var xStudy2 = null;
var xStudy3 = null;
var bInit = false; // Initialization flag
function main() {
if (bInit == false) {
xStudy1 = adx(14, 14, inv(20)); // 20-min interval
xStudy2 = pdi(14, 14, inv(20)); // 20-min interval
xStudy3 = ndi(14, 14, inv(20)); // 20-min interval
bInit = true;
} // retrieve single values for conditional statements
var nValue1_0 = xStudy1.getValue(0); // Current Bar Index value
var nValue1_1 = xStudy1.getValue(-1); // Prior Bar Index value
// Synchronized Series plot
return new Array(getSeries(xStudy1), getSeries(xStudy2), getSeries(xStudy3));
}```

Initialize a Series Object based on an external symbol and interval:
```// global Series Object variables
var xStudy1 = null;
var xStudy2 = null;
var xStudy3 = null;
var bInit = false; // Initialization flag
function main() {
if (bInit == false) {
xStudy1 = adx(14, 14, sym("IBM,20")); // IBM 20-min interval
xStudy2 = pdi(14, 14, sym("IBM,20")); // IBM 20-min interval
xStudy3 = ndi(14, 14, sym("IBM,20")); // IBM 20-min interval
bInit = true;
} // retrieve single values for conditional statements
var nValue1_0 = xStudy1.getValue(0); // Current Bar Index value
var nValue1_1 = xStudy1.getValue(-1); // Prior Bar Index value
// Synchronized Series plot
return new Array(getSeries(xStudy1), getSeries(xStudy2), getSeries(xStudy3));
}```