npm package: @stdlib/array-base-banded-to-compact
Description: Convert a two-dimensional banded nested array to compact banded storage.
Author: The Stdlib Authors
Latest version: 0.1.1

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# toCompact

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> Convert a two-dimensional banded nested array to compact banded storage.

<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->

<section class="intro">

</section>

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<!-- Package usage documentation. -->

<section class="installation">

## Installation

```bash
npm install @stdlib/array-base-banded-to-compact
```

</section>

<section class="usage">

## Usage

```javascript
var toCompact = require( '@stdlib/array-base-banded-to-compact' );
```

#### toCompact( arr, ku, kl, colexicographic )

Converts a two-dimensional banded nested array to compact banded storage.

```javascript
var x = [ [ -1, 2, 0 ], [ 2, -2, 4 ], [ 0, 4, -3 ] ];

var out = toCompact( x, 1, 1, false );
// returns [ [ 0, 2, 4 ], [ -1, -2, -3 ], [ 2, 4, 0 ] ]
```

The function accepts the following arguments:

-   **arr**: input two-dimensional nested array.
-   **ku**: number of super-diagonals.
-   **kl**: number of sub-diagonals.
-   **colexicographic**: boolean specifying whether to store diagonals in colexicographic access order.

</section>

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<section class="notes">

</section>

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<section class="examples">

## Examples

<!-- eslint-disable no-multi-spaces -->

<!-- eslint no-undef: "error" -->

```javascript
var toCompact = require( '@stdlib/array-base-banded-to-compact' );

// Define a banded matrix:
var A = [
    [  1,  2,  3,   0,  0 ],
    [ -2,  4,  5,   6,  0 ],
    [ -3, -5,  7,   8,  9 ],
    [  0, -6, -8,  10, 11 ],
    [  0,  0, -9, -11, 12 ]
];

// Convert the matrix to lexicographic compact form:
var AC = toCompact( A, 2, 2, false );
/* e.g., returns =>
    [
        [  0,  0,  3,   6,  9 ],
        [  0,  2,  5,   8, 11 ],
        [  1,  4,  7,  10, 12 ],
        [ -2, -5, -8, -11,  0 ],
        [ -3, -6, -9,   0,  0 ]
    ]
*/

AC = toCompact( A, 2, 1, false );
/* e.g., returns =>
    [
        [  0,  0,  3,   6,  9 ],
        [  0,  2,  5,   8, 11 ],
        [  1,  4,  7,  10, 12 ],
        [ -2, -5, -8, -11,  0 ]
    ]
*/

AC = toCompact( A, 1, 2, false );
/* e.g., returns =>
    [
        [  0,  2,  5,   8, 11 ],
        [  1,  4,  7,  10, 12 ],
        [ -2, -5, -8, -11,  0 ],
        [ -3, -6, -9,   0,  0 ]
    ]
*/

// Convert the matrix to colexicographic compact form:
AC = toCompact( A, 2, 2, true );
/* e.g., returns =>
    [
        [ 0,  0,  1,  -2, -3 ],
        [ 0,  2,  4,  -5, -6 ],
        [ 3,  5,  7,  -8, -9 ],
        [ 6,  8, 10, -11,  0 ],
        [ 9, 11, 12,   0,  0 ]
    ]
*/
```

</section>

<!-- /.examples -->

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* * *

## Notice

This package is part of [stdlib][stdlib], a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

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## License

See [LICENSE][stdlib-license].


## Copyright

Copyright &copy; 2016-2026. The Stdlib [Authors][stdlib-authors].

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