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dlinspace

Fill a double-precision floating-point strided array with linearly spaced values over a specified interval.

Installation

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

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

dlinspace( N, start, stop, endpoint, x, strideX )

Fills a double-precision floating-point strided array with linearly spaced values over a specified interval.

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

var x = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

dlinspace( x.length, 0.0, 7.0, true, x, 1 );
// x => <Float64Array>[ 0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0 ]

The function has the following parameters:

• N: number of indexed elements.
• start: start of interval.
• stop: end of interval.
• endpoint: boolean indicating whether to include the stop value when writing values to the input array. If true, the input array is filled with evenly spaced values over the closed interval [start, stop]. If false, the input array is filled with evenly spaced values over the half-open interval [start, stop).
• 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( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

dlinspace( 4, 1.0, 5.0, false, x, 2 );
// x => <Float64Array>[ 1.0, 0.0, 2.0, 0.0, 3.0, 0.0, 4.0, 0.0 ]

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( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

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

// Fill every other element...
dlinspace( 3, 1.0, 3.0, true, x1, 2 );
// x0 => <Float64Array>[ 0.0, 1.0, 0.0, 2.0, 0.0, 3.0 ]

dlinspace.ndarray( N, start, stop, endpoint, x, strideX, offsetX )

Fills a double-precision floating-point strided array with linearly spaced values over a specified interval using alternative indexing semantics.

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

var x = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

dlinspace.ndarray( x.length, 0.0, 7.0, true, x, 1, 0 );
// x => <Float64Array>[ 0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0 ]

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( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

dlinspace.ndarray( 3, 1.0, 3.0, true, x, 1, x.length-3 );
// x => <Float64Array>[ 0.0, 0.0, 0.0, 1.0, 2.0, 3.0 ]

Notes

• Let M be the number of generated values (which is either N or N+1 depending on whether endpoint is true or false, respectively). The spacing between values is thus given by Δ = (stop-start)/(M-1).
• If N <= 0, both functions return x unchanged.

Examples

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

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

dlinspace( x.length, 0.0, 10.0, true, x, 1 );
console.log( x );

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C APIs

Usage

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

stdlib_strided_dlinspace( N, start, stop, endpoint, *X, strideX )

Fills a double-precision floating-point strided array with linearly spaced values over a specified interval.

#include <stdbool.h>

double x[] = { 0.0, 0.0, 0.0, 0.0 };

stdlib_strided_dlinspace( 4, 1.0, 5.0, true, x, 1 );

The function accepts the following arguments:

• N: [in] CBLAS_INT number of indexed elements.
• start: [in] double start of interval.
• stop: [in] double end of interval.
• endpoint: [in] bool boolean indicating whether to include the stop value when writing values to the input array. If true, the input array is filled with evenly spaced values over the closed interval [start, stop]. If false, the input array is filled with evenly spaced values over the half-open interval [start, stop).
• X: [out] double* input array.
• strideX: [in] CBLAS_INT stride length.

void stdlib_strided_dlinspace( const CBLAS_INT N, const double start, const double stop, const bool endpoint, double *X, const CBLAS_INT strideX );

stdlib_strided_dlinspace_ndarray( N, start, stop, endpoint, *X, strideX, offsetX )

Fills a double-precision floating-point strided array with linearly spaced values over a specified interval using alternative indexing semantics.

#include <stdbool.h>

double x[] = { 0.0, 0.0, 0.0, 0.0 };

stdlib_strided_dlinspace_ndarray( 4, 1.0, 5.0, true, x, 1, 0 );

The function accepts the following arguments:

• N: [in] CBLAS_INT number of indexed elements.
• start: [in] double start of interval.
• stop: [in] double end of interval.
• endpoint: [in] bool boolean indicating whether to include the stop value when writing values to the input array. If true, the input array is filled with evenly spaced values over the closed interval [start, stop]. If false, the input array is filled with evenly spaced values over the half-open interval [start, stop).
• X: [out] double* input array.
• strideX: [in] CBLAS_INT stride length.
• offsetX: [in] CBLAS_INT starting index.

void stdlib_strided_dlinspace_ndarray( const CBLAS_INT N, const double start, const double stop, const bool endpoint, double *X, const CBLAS_INT strideX, const CBLAS_INT offsetX );

Examples

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

int main( void ) {
    // Create a strided array:
    double x[] = { 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 = 8;

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

    // Fill the array:
    stdlib_strided_dlinspace( N, 0.0, 10.0, true, x, strideX );

    // Print the result:
    for ( int i = 0; i < 8; i++ ) {
        printf( "x[ %i ] = %lf\n", i, x[ 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 © 2016-2025. The Stdlib Authors.