@stdlib/blas-ext-base-dfill

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dfill

Fill a double-precision floating-point strided array with a specified scalar constant.

Installation

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

Usage

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

dfill( N, alpha, x, strideX )

Fills a double-precision floating-point strided array with a specified scalar constant.

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

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

dfill( x.length, 5.0, x, 1 );
// x => <Float64Array>[ 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0 ]

The function has the following parameters:

• N: number of indexed elements.
• alpha: scalar constant.
• x: input Float64Array.
• strideX: stride length.

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

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

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

dfill( 4, 5.0, x, 2 );
// x => <Float64Array>[ 5.0, 1.0, 5.0, -5.0, 5.0, 0.0, 5.0, -3.0 ]

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

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

// Initial array...
var x0 = new Float64Array( [ 1.0, -2.0, 3.0, -4.0, 5.0, -6.0 ] );

// Create an offset view...
var x1 = new Float64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element

// Fill every other element...
dfill( 3, 5.0, x1, 2 );
// x0 => <Float64Array>[ 1.0, 5.0, 3.0, 5.0, 5.0, 5.0 ]

dfill.ndarray( N, alpha, x, strideX, offsetX )

Fills a double-precision floating-point strided array with a specified scalar constant using alternative indexing semantics.

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

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

dfill.ndarray( x.length, 5.0, x, 1, 0 );
// x => <Float64Array>[ 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0, 5.0 ]

The function has the following additional parameters:

• offsetX: starting index.

While typed array views mandate a view offset based on the underlying buffer, the offset parameter supports indexing semantics based on a starting index. For example, to access only the last three elements:

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

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

dfill.ndarray( 3, 5.0, x, 1, x.length-3 );
// x => <Float64Array>[ 1.0, -2.0, 3.0, 5.0, 5.0, 5.0 ]

Notes

• If N <= 0, both functions return x unchanged.

Examples

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

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

dfill( x.length, 5.0, x, 1 );
console.log( x );

C APIs

Usage

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

stdlib_strided_dfill( N, alpha, *X, strideX )

Fills a double-precision floating-point strided array with a specified scalar constant.

double x[] = { 1.0, 2.0, 3.0, 4.0 };

stdlib_strided_dfill( 4, 5.0, x, 1 );

The function accepts the following arguments:

• N: [in] CBLAS_INT number of indexed elements.
• alpha: [in] double scalar constant.
• X: [out] double* input array.
• strideX: [in] CBLAS_INT stride length.

void stdlib_strided_dfill( const CBLAS_INT N, const double alpha, double *X, const CBLAS_INT strideX );

stdlib_strided_dfill_ndarray( N, alpha, *X, strideX, offsetX )

Fills a double-precision floating-point strided array with a specified scalar constant using alternative indexing semantics.

double x[] = { 1.0, 2.0, 3.0, 4.0 };

stdlib_strided_dfill_ndarray( 4, 5.0, x, 1, 0 );

The function accepts the following arguments:

• N: [in] CBLAS_INT number of indexed elements.
• alpha: [in] double scalar constant.
• X: [out] double* input array.
• strideX: [in] CBLAS_INT stride length.
• offsetX: [in] CBLAS_INT starting index.

void stdlib_strided_dfill_ndarray( const CBLAS_INT N, const double alpha, double *X, const CBLAS_INT strideX, const CBLAS_INT offsetX );

Examples

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

int main( void ) {
    // Create a strided array:
    double x[] = { 1.0, -2.0, 3.0, -4.0, 5.0, -6.0, 7.0, -8.0 };

    // Specify the number of indexed elements:
    const int N = 8;

    // Specify a stride:
    const int strideX = 1;

    // Fill the array:
    stdlib_strided_dfill( N, 5.0, x, strideX );

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

See Also

• @stdlib/blas-ext/base/gfill: fill a strided array with a specified scalar constant.
• @stdlib/blas-ext/base/sfill: fill a single-precision floating-point strided array with a specified scalar constant.

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

License

See LICENSE.

Copyright

Copyright © 2016-2026. The Stdlib Authors.