glinspace

Fill a strided array with linearly spaced values over a specified interval.

Installation

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

Usage

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

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

Fills a strided array with linearly spaced values over a specified interval.

var x = [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ];

glinspace( x.length, 0.0, 7.0, true, x, 1 );
// x => [ 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 array.
• 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 x = [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ];

glinspace( 4, 1.0, 5.0, false, x, 2 );
// x => [ 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...
glinspace( 3, 1.0, 3.0, true, x1, 2 );
// x0 => <Float64Array>[ 0.0, 1.0, 0.0, 2.0, 0.0, 3.0 ]

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

Fills a strided array with linearly spaced values over a specified interval using alternative indexing semantics.

var x = [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ];

glinspace.ndarray( x.length, 0.0, 7.0, true, x, 1, 0 );
// x => [ 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 x = [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ];

glinspace.ndarray( 3, 1.0, 3.0, true, x, 1, x.length-3 );
// x => [ 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)

• When the number of generated values is greater than 1 and endpoint is true, the set of values written to a provided input array is guaranteed to include the start and stop values. Beware, however, that values between start and stop are subject to floating-point rounding errors. Hence,

  var x = [ 0.0, 0.0, 0.0 ];
  
  glinspace( 3, 0.0, 1.0, true, x, 1 );
  // x => [ 0.0, ~0.5, 1.0 ]

  where x[1] is only guaranteed to be approximately equal to 0.5.

• When N = 1 and endpoint is false, only the start value is written to a provided input array. When N = 1 and endpoint is true, only the stop value is written to a provided input array.

• If start < stop, values are written to a provided input array in ascending order; otherwise, values are written in descending order.

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

Examples

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

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

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

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.