# ind2sub
> Convert a linear index to an array of subscripts.
## Usage
```javascript
var ind2sub = require( '@stdlib/ndarray/ind2sub' );
```
#### ind2sub( shape, idx\[, options] )
Converts a linear index to an array of subscripts.
```javascript
var shape = [ 2, 2 ];
var s = ind2sub( shape, 2 );
// returns [ 1, 0 ]
```
The function supports the following `options`:
- `mode`: specifies how to handle a linear index which exceeds array dimensions. The following modes are supported:
- `throw`: specifies that the function should throw an error when a linear index exceeds array dimensions.
- `wrap`: specifies that the function should wrap around a linear index exceeding array dimensions using modulo arithmetic.
- `clamp`: specifies that the function should set a linear index exceeding array dimensions to either `0` (minimum linear index) or the maximum linear index.
- `order`: specifies whether an array is `row-major` (C-style) or `column-major` (Fortran-style). Default: `'row-major'`.
By default, the function assumes a row-major array. To return subscripts for a column-major array, set the `order` option.
```javascript
var shape = [ 2, 2 ];
var opts = {};
opts.order = 'column-major';
var s = ind2sub( shape, 1, opts );
// returns [ 1, 0 ]
```
By default, the function throws an `error` if provided a linear index which exceeds array dimensions. To specify alternative behavior, set the `mode` option.
```javascript
var shape = [ 2, 2 ];
var opts = {};
opts.mode = 'wrap';
var s = ind2sub( shape, -5, opts );
// returns [ 1, 1 ]
opts.mode = 'clamp';
s = ind2sub( shape, 7, opts );
// returns [ 1, 1 ]
```
#### ind2sub.assign( shape, idx\[, options], out )
Converts a linear index to an array of subscripts and assigns results to a provided output array.
```javascript
var shape = [ 2, 2 ];
var out = [ 0, 0 ];
var subscripts = ind2sub.assign( shape, 1, out );
// returns [ 0, 1 ]
var bool = ( subscripts === out );
// returns true
```
The function accepts the same `options` as above.
## Examples
```javascript
var numel = require( '@stdlib/ndarray/base/numel' );
var ind2sub = require( '@stdlib/ndarray/ind2sub' );
var shape = [ 3, 3, 3 ];
var len = numel( shape );
var arr = [];
var i;
for ( i = 0; i < len; i++ ) {
arr.push( i );
}
var opts = {
'order': 'column-major'
};
console.log( '' );
console.log( 'Dimensions: %s.', shape.join( 'x' ) );
console.log( 'View (subscripts):' );
console.log( '' );
var row;
var s;
row = ' ';
for ( i = 0; i < len; i++ ) {
s = ind2sub( shape, i, opts );
row += '(' + s.join( ',' ) + ')';
if ( (i+1)%shape[0] === 0 ) {
console.log( row );
row = ' ';
} else {
row += ', ';
}
if ( (i+1)%(shape[0]*shape[1]) === 0 ) {
console.log( '' );
}
}
```