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dreplicate

Replicate each element in a double-precision floating-point strided array a specified number of times.

Installation

npm install @stdlib/blas-ext-base-dreplicate

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 dreplicate = require( '@stdlib/blas-ext-base-dreplicate' );

dreplicate( N, k, x, strideX, out, strideOut )

Replicates each element in a double-precision floating-point strided array a specified number of times.

var Float64Array = require( '@stdlib/array-float64' );

var x = new Float64Array( [ 1.0, 2.0, 3.0 ] );
var out = new Float64Array( 6 );

dreplicate( x.length, 2, x, 1, out, 1 );
// out => <Float64Array>[ 1.0, 1.0, 2.0, 2.0, 3.0, 3.0 ]

The function has the following parameters:

• N: number of indexed elements.
• k: number of times to replicate each element.
• x: input Float64Array.
• strideX: stride length for x.
• out: output Float64Array.
• strideOut: stride length for out.

The N and stride parameters determine which elements in the strided arrays are accessed at runtime. For example, to replicate every other element:

var Float64Array = require( '@stdlib/array-float64' );

var x = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );
var out = new Float64Array( 6 );

dreplicate( 3, 2, x, 2, out, 1 );
// out => <Float64Array>[ 1.0, 1.0, 3.0, 3.0, 5.0, 5.0 ]

Note that indexing is relative to the first index. To introduce an offset, use typed array views.

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 out0 = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

// Create offset views...
var x1 = new Float64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
var out1 = new Float64Array( out0.buffer, out0.BYTES_PER_ELEMENT*2 ); // start at 3rd element

dreplicate( 3, 2, x1, 2, out1, 1 );
// out0 => <Float64Array>[ 0.0, 0.0, 2.0, 2.0, 4.0, 4.0, 6.0, 6.0 ]

dreplicate.ndarray( N, k, x, strideX, offsetX, out, strideOut, offsetOut )

Replicates each element in a double-precision floating-point strided array a specified number of times using alternative indexing semantics.

var Float64Array = require( '@stdlib/array-float64' );

var x = new Float64Array( [ 1.0, 2.0, 3.0 ] );
var out = new Float64Array( 6 );

dreplicate.ndarray( x.length, 2, x, 1, 0, out, 1, 0 );
// out => <Float64Array>[ 1.0, 1.0, 2.0, 2.0, 3.0, 3.0 ]

The function has the following additional parameters:

• offsetX: starting index for x.
• offsetOut: starting index for out.

While typed array views mandate a view offset based on the underlying buffer, offset parameters support indexing semantics based on starting indices. For example, to replicate every other element in the strided input array starting from the second element and to store in the last N*k elements of the strided output array starting from the last element:

var Float64Array = require( '@stdlib/array-float64' );

var x = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );
var out = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

dreplicate.ndarray( 3, 2, x, 2, 1, out, -1, out.length-1 );
// out => <Float64Array>[ 0.0, 0.0, 6.0, 6.0, 4.0, 4.0, 2.0, 2.0 ]

Notes

• If N <= 0 or k <= 0, both functions return out unchanged.
• Both functions assume that the output array supports N*k indexed elements.

Examples

var discreteUniform = require( '@stdlib/random-array-discrete-uniform' );
var Float64Array = require( '@stdlib/array-float64' );
var dreplicate = require( '@stdlib/blas-ext-base-dreplicate' );

var x = discreteUniform( 10, -100, 100, {
    'dtype': 'float64'
});
console.log( x );

var out = new Float64Array( x.length * 3 );
console.log( out );

dreplicate( x.length, 3, x, 1, out, 1 );
console.log( out );

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C APIs

Usage

#include "stdlib/blas/ext/base/dreplicate.h"

stdlib_strided_dreplicate( N, k, *X, strideX, *Out, strideOut )

Replicates each element in a double-precision floating-point strided array a specified number of times.

const double x[] = { 1.0, 2.0, 3.0 };
double out[] = { 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 };

stdlib_strided_dreplicate( 3, 2, x, 1, out, 1 );

The function accepts the following arguments:

• N: [in] CBLAS_INT number of indexed elements.
• k: [in] CBLAS_INT number of times to replicate each element.
• X: [in] double* input array.
• strideX: [in] CBLAS_INT stride length for X.
• Out: [out] double* output array.
• strideOut: [in] CBLAS_INT stride length for Out.

void stdlib_strided_dreplicate( const CBLAS_INT N, const CBLAS_INT k, const double *X, const CBLAS_INT strideX, double *Out, const CBLAS_INT strideOut );

stdlib_strided_dreplicate_ndarray( N, k, *X, strideX, offsetX, *Out, strideOut, offsetOut )

Replicates each element in a double-precision floating-point strided array a specified number of times using alternative indexing semantics.

const double x[] = { 1.0, 2.0, 3.0 };
double out[] = { 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 };

stdlib_strided_dreplicate_ndarray( 3, 2, x, 1, 0, out, 1, 0 );

The function accepts the following arguments:

• N: [in] CBLAS_INT number of indexed elements.
• k: [in] CBLAS_INT number of times to replicate each element.
• X: [in] double* input array.
• strideX: [in] CBLAS_INT stride length for X.
• offsetX: [in] CBLAS_INT starting index for X.
• Out: [out] double* output array.
• strideOut: [in] CBLAS_INT stride length for Out.
• offsetOut: [in] CBLAS_INT starting index for Out.

void stdlib_strided_dreplicate_ndarray( const CBLAS_INT N, const CBLAS_INT k, const double *X, const CBLAS_INT strideX, const CBLAS_INT offsetX, double *Out, const CBLAS_INT strideOut, const CBLAS_INT offsetOut );

Examples

#include "stdlib/blas/ext/base/dreplicate.h"
#include <stdio.h>

int main( void ) {
    // Create strided arrays:
    const double x[] = { 1.0, 2.0, 3.0, 4.0 };
    double out[] = { 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 };

    // Specify the number of indexed elements:
    const int N = 4;

    // Specify the number of times to replicate each element:
    const int k = 2;

    // Specify strides:
    const int strideX = 1;
    const int strideOut = 1;

    // Replicate each element:
    stdlib_strided_dreplicate( N, k, x, strideX, out, strideOut );

    // Print the results:
    for ( int i = 0; i < 8; i++ ) {
        printf( "Out[ %i ] = %lf\n", i, out[ i ] );
    }
}

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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 © 2016-2026. The Stdlib Authors.