# Wrap Index
> Wrap an index on the interval `[0,max]`.
## Usage
```javascript
var wrapIndex = require( '@stdlib/ndarray/base/wrap-index' );
```
#### wrapIndex( idx, max )
Wrap an index on the interval `[0,max]`.
```javascript
var idx = wrapIndex( 2, 10 );
// returns 2
idx = wrapIndex( -5, 10 );
// returns 6
idx = wrapIndex( 15, 10 );
// returns 4
```
## Examples
```javascript
var discreteUniform = require( '@stdlib/random/base/discrete-uniform' );
var wrapIndex = require( '@stdlib/ndarray/base/wrap-index' );
var idx;
var out;
var i;
for ( i = 0; i < 100; i++ ) {
idx = discreteUniform( -20, 20 );
out = wrapIndex( idx, 9 );
console.log( '%d => [%d,%d] => %d', idx, 0, 9, out );
}
```