Copy values from x into y.
npm install @stdlib/blas-base-dcopyWe believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js. The library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases. When you use stdlib, you can be absolutely certain that you are using the most thorough, rigorous, well-written, studied, documented, tested, measured, and high-quality code out there. To join us in bringing numerical computing to the web, get started by checking us out on GitHub, and please consider financially supporting stdlib. We greatly appreciate your continued support!
About stdlib...
[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url]
> Copy values from x into y.
``bash`
npm install @stdlib/blas-base-dcopy
`javascript`
var dcopy = require( '@stdlib/blas-base-dcopy' );
#### dcopy( N, x, strideX, y, strideY )
Copies values from x into y.
`javascript
var Float64Array = require( '@stdlib/array-float64' );
var x = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0 ] );
var y = new Float64Array( [ 6.0, 7.0, 8.0, 9.0, 10.0 ] );
dcopy( x.length, x, 1, y, 1 );
// y =>
`
The function has the following parameters:
- N: number of indexed elements.
- x: input [Float64Array][mdn-float64array].x
- strideX: index increment for .Float64Array
- y: output [][mdn-float64array].y
- strideY: index increment for .
The N and stride parameters determine how values from x are copied into y. For example, to copy in reverse order every other value in x into the first N elements of y,
`javascript
var Float64Array = require( '@stdlib/array-float64' );
var x = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );
var y = new Float64Array( [ 7.0, 8.0, 9.0, 10.0, 11.0, 12.0 ] );
dcopy( 3, x, -2, y, 1 );
// y =>
`
Note that indexing is relative to the first index. To introduce an offset, use [typed array][mdn-typed-array] views.
`javascript
var Float64Array = require( '@stdlib/array-float64' );
// Initial arrays...
var x0 = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );
var y0 = new Float64Array( [ 7.0, 8.0, 9.0, 10.0, 11.0, 12.0 ] );
// Create offset views...
var x1 = new Float64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
var y1 = new Float64Array( y0.buffer, y0.BYTES_PER_ELEMENT*3 ); // start at 4th element
// Copy in reverse order every other value from x1 into y1...`
dcopy( 3, x1, -2, y1, 1 );
// y0 =>
#### dcopy.ndarray( N, x, strideX, offsetX, y, strideY, offsetY )
Copies values from x into y using alternative indexing semantics.
`javascript
var Float64Array = require( '@stdlib/array-float64' );
var x = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0 ] );
var y = new Float64Array( [ 6.0, 7.0, 8.0, 9.0, 10.0 ] );
dcopy.ndarray( x.length, x, 1, 0, y, 1, 0 );
// y =>
`
The function has the following additional parameters:
- offsetX: starting index for x.y
- offsetY: starting index for .
While [typed array][mdn-typed-array] views mandate a view offset based on the underlying buffer, the offset parameters support indexing semantics based on starting indices. For example, to copy every other value in x starting from the second value into the last N elements in y where x[i] = y[n], x[i+2] = y[n-1],...,
`javascript
var Float64Array = require( '@stdlib/array-float64' );
var x = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );
var y = new Float64Array( [ 7.0, 8.0, 9.0, 10.0, 11.0, 12.0 ] );
dcopy.ndarray( 3, x, 2, 1, y, -1, y.length-1 );
// y =>
`
- If N <= 0, both functions return y unchanged.dcopy()
- corresponds to the [BLAS][blas] level 1 function [dcopy][dcopy].
`javascript
var discreteUniform = require( '@stdlib/random-array-discrete-uniform' );
var dcopy = require( '@stdlib/blas-base-dcopy' );
var opts = {
'dtype': 'float64'
};
var x = discreteUniform( 10, 0, 500, opts );
console.log( x );
var y = discreteUniform( x.length, 0, 255, opts );
console.log( y );
// Copy elements from x into y starting from the end of y:`
dcopy( x.length, x, 1, y, -1 );
console.log( y );
*
`c`
#include "stdlib/blas/base/dcopy.h"
#### c_dcopy( N, \X, strideX, \Y, strideY )
Copies values from X into Y.
`c
const double x[] = { 1.0, 2.0, 3.0, 4.0 };
double y[] = { 0.0, 0.0, 0.0, 0.0 };
c_dcopy( 4, x, 1, y, 1 );
`
The function accepts the following arguments:
- N: [in] CBLAS_INT number of indexed elements.[in] double*
- X: input array.[in] CBLAS_INT
- strideX: index increment for X.[out] double*
- Y: output array.[in] CBLAS_INT
- strideY: index increment for Y.
`c`
void c_dcopy( const CBLAS_INT N, const double X, const CBLAS_INT strideX, double Y, const CBLAS_INT strideY );
#### c_dcopy_ndarray( N, \X, strideX, offsetX, \Y, strideY, offsetY )
Copies values from x into y using alternative indexing semantics.
`c
double x[] = { 1.0, 2.0, 3.0, 4.0, 5.0 };
double y[] = { 0.0, 0.0, 0.0, 0.0, 0.0 };
c_dcopy_ndarray( 3, x, 1, 2, y, 1, 2 );
`
The function accepts the following arguments:
- N: [in] CBLAS_INT number of indexed elements.[in] double*
- X: input array.[in] CBLAS_INT
- strideX: index increment for X.[in] CBLAS_INT
- offsetX: starting index for X.[out] double*
- Y: output array.[in] CBLAS_INT
- strideY: index increment for Y.[in] CBLAS_INT
- offsetY: starting index for Y.
`c`
void c_dcopy_ndarray( const CBLAS_INT N, const double X, const CBLAS_INT strideX, const CBLAS_INT offsetX, double Y, const CBLAS_INT strideY, const CBLAS_INT offsetY );
`c
#include "stdlib/blas/base/dcopy.h"
#include
int main( void ) {
// Create strided arrays:
const double x[] = { 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 };
double y[] = { 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 };
// Specify the number of elements:
const int N = 4;
// Specify stride lengths:
const int strideX = 2;
const int strideY = -2;
// Copy elements:
c_dcopy( N, x, strideX, y, strideY );
// Print the result:
for ( int i = 0; i < 8; i++ ) {
printf( "y[ %i ] = %lf\n", i, y[ i ] );
}
// Copy elements:
c_dcopy_ndarray( N, x, strideX, 0, y, strideY, 6 );
// Print the result:
for ( int i = 0; i < 8; i++ ) {
printf( "y[ %i ] = %lf\n", i, y[ i ] );
}
}
`
*
- [@stdlib/blas-base/dswap][@stdlib/blas/base/dswap]: interchange two double-precision floating-point vectors.
- [@stdlib/blas-base/gcopy][@stdlib/blas/base/gcopy]: copy values from x into y.
- [@stdlib/blas-base/scopy][@stdlib/blas/base/scopy]: copy values from x into y.
*
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.
For more information on the project, filing bug reports and feature requests, and guidance on how to develop [stdlib][stdlib], see the main project [repository][stdlib].
#### Community
[![Chat][chat-image]][chat-url]
---
See [LICENSE][stdlib-license].
Copyright © 2016-2026. The Stdlib [Authors][stdlib-authors].
[npm-image]: http://img.shields.io/npm/v/@stdlib/blas-base-dcopy.svg
[npm-url]: https://npmjs.org/package/@stdlib/blas-base-dcopy
[test-image]: https://github.com/stdlib-js/blas-base-dcopy/actions/workflows/test.yml/badge.svg?branch=v0.4.1
[test-url]: https://github.com/stdlib-js/blas-base-dcopy/actions/workflows/test.yml?query=branch:v0.4.1
[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/blas-base-dcopy/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/blas-base-dcopy?branch=main
[chat-image]: https://img.shields.io/badge/zulip-join_chat-brightgreen.svg
[chat-url]: https://stdlib.zulipchat.com
[stdlib]: https://github.com/stdlib-js/stdlib
[stdlib-authors]: https://github.com/stdlib-js/stdlib/graphs/contributors
[umd]: https://github.com/umdjs/umd
[es-module]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules
[deno-url]: https://github.com/stdlib-js/blas-base-dcopy/tree/deno
[deno-readme]: https://github.com/stdlib-js/blas-base-dcopy/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/blas-base-dcopy/tree/umd
[umd-readme]: https://github.com/stdlib-js/blas-base-dcopy/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/blas-base-dcopy/tree/esm
[esm-readme]: https://github.com/stdlib-js/blas-base-dcopy/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/blas-base-dcopy/blob/main/branches.md
[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/blas-base-dcopy/main/LICENSE
[blas]: http://www.netlib.org/blas
[dcopy]: http://www.netlib.org/lapack/explore-html/de/da4/group__double__blas__level1.html
[mdn-float64array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Float64Array
[mdn-typed-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray
[@stdlib/blas/base/dswap]: https://www.npmjs.com/package/@stdlib/blas-base-dswap
[@stdlib/blas/base/gcopy]: https://www.npmjs.com/package/@stdlib/blas-base-gcopy
[@stdlib/blas/base/scopy]: https://www.npmjs.com/package/@stdlib/blas-base-scopy