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factory

Return a function which interchanges two vectors.

Installation

npm install @stdlib/blas-tools-swap-factory

Alternatively,

• To load the package in a website via a script tag without installation and bundlers, use the ES Module available on the esm branch (see README).
• If you are using Deno, visit the deno branch (see README for usage intructions).
• For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the umd branch (see README).

The branches.md file summarizes the available branches and displays a diagram illustrating their relationships.

To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.

Usage

var factory = require( '@stdlib/blas-tools-swap-factory' );

factory( base, dtype )

Returns a function which interchanges two vectors.

var dswap = require( '@stdlib/blas-base-dswap' ).ndarray;

var swap = factory( dswap, 'float64' );

The function has the following parameters:

• base: "base" function which interchanges two vectors. Must have an ndarray function signature (i.e., must support index offsets).
• dtype: array data type. The function assumes that the data type of all provided arrays is the same.

swap( x, y[, dim] )

Interchanges two vectors.

var Float64Array = require( '@stdlib/array-float64' );
var array = require( '@stdlib/ndarray-array' );
var dswap = require( '@stdlib/blas-base-dswap' ).ndarray;

var swap = factory( dswap, 'float64' );

var x = array( new Float64Array( [ 4.0, 2.0, -3.0, 5.0, -1.0 ] ) );
var y = array( new Float64Array( [ 2.0, 6.0, -1.0, -4.0, 8.0 ] ) );

swap( x, y );

var xbuf = x.data;
// returns <Float64Array>[ 2.0, 6.0, -1.0, -4.0, 8.0 ]

var ybuf = y.data;
// returns <Float64Array>[ 4.0, 2.0, -3.0, 5.0, -1.0 ]

The returned function has the following parameters:

• x: a non-zero-dimensional ndarray. Must have the same shape as y.
• y: a non-zero-dimensional ndarray. Must have the same shape as x.
• dim: dimension along which to interchange vectors. Must be a negative integer. Negative indices are resolved relative to the last array dimension, with the last dimension corresponding to -1. Default: -1.

For multi-dimensional input ndarrays, the function performs batched computation, such that the function interchanges each pair of vectors in x and y according to the specified dimension index.

var Float64Array = require( '@stdlib/array-float64' );
var array = require( '@stdlib/ndarray-array' );
var dswap = require( '@stdlib/blas-base-dswap' ).ndarray;

var swap = factory( dswap, 'float64' );

var opts = {
    'shape': [ 2, 3 ]
};
var x = array( new Float64Array( [ 4.0, 2.0, -3.0, 5.0, -1.0, 3.0 ] ), opts );
var y = array( new Float64Array( [ 2.0, 6.0, -1.0, -4.0, 8.0, 2.0 ] ), opts );

var v1 = x.get( 0, 0 );
// returns 4.0

var v2 = y.get( 0, 0 );
// returns 2.0

swap( x, y );

v1 = x.get( 0, 0 );
// returns 2.0

v2 = y.get( 0, 0 );
// returns 4.0

Notes

For the returned function,

• Both input ndarrays must have the same shape.
• Negative indices are resolved relative to the last ndarray dimension, with the last dimension corresponding to -1.
• For multi-dimensional ndarrays, batched computation effectively means swapping all of x with all of y; however, the choice of dim will significantly affect performance. For best performance, specify a dim which best aligns with the memory layout of provided ndarrays.

Examples

var discreteUniform = require( '@stdlib/random-array-discrete-uniform' );
var ndarray2array = require( '@stdlib/ndarray-to-array' );
var array = require( '@stdlib/ndarray-array' );
var dswap = require( '@stdlib/blas-base-dswap' ).ndarray;
var factory = require( '@stdlib/blas-tools-swap-factory' );

var swap = factory( dswap, 'float64' );

var opts = {
    'dtype': 'float64'
};

var x = array( discreteUniform( 10, 0, 100, opts ), {
    'shape': [ 5, 2 ]
});
console.log( ndarray2array( x ) );

var y = array( discreteUniform( 10, 0, 10, opts ), {
    'shape': x.shape
});
console.log( ndarray2array( y ) );

swap( x, y );
console.log( ndarray2array( x ) );
console.log( ndarray2array( y ) );

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Notice

This package is part of 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.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.

Community

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License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.