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Apply a unary function to a double-precision floating-point strided input array and assign results to a double-precision floating-point strided output array.
To use in Observable,
dmap = require( 'https://cdn.jsdelivr.net/gh/stdlib-js/strided-base-dmap@umd/browser.js' )To vendor stdlib functionality and avoid installing dependency trees for Node.js, you can use the UMD server build:
var dmap = require( 'path/to/vendor/umd/strided-base-dmap/index.js' )To include the bundle in a webpage,
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/strided-base-dmap@umd/browser.js"></script>If no recognized module system is present, access bundle contents via the global scope:
<script type="text/javascript">
(function () {
window.dmap;
})();
</script>Applies a unary function to a double-precision floating-point strided input array and assigns results to a double-precision floating-point strided output array.
var Float64Array = require( '@stdlib/array-float64' );
var abs = require( '@stdlib/math-base-special-abs' );
var x = new Float64Array( [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, -3.0 ] );
// Compute the absolute values in-place:
dmap( x.length, x, 1, x, 1, abs );
// x => <Float64Array>[ 2.0, 1.0, 3.0, 5.0, 4.0, 0.0, 1.0, 3.0 ]The function accepts the following arguments:
- N: number of indexed elements.
- x: input
Float64Array. - strideX: index increment for
x. - y: output
Float64Array. - strideY: index increment for
y. - fcn: function to apply.
The N and stride parameters determine which elements in x and y are accessed at runtime. For example, to index every other value in x and to index the first N elements of y in reverse order,
var Float64Array = require( '@stdlib/array-float64' );
var abs = require( '@stdlib/math-base-special-abs' );
var x = new Float64Array( [ -1.0, -2.0, -3.0, -4.0, -5.0, -6.0 ] );
var y = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );
dmap( 3, x, 2, y, -1, abs );
// y => <Float64Array>[ 5.0, 3.0, 1.0, 0.0, 0.0, 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' );
var abs = require( '@stdlib/math-base-special-abs' );
// Initial arrays...
var x0 = new Float64Array( [ -1.0, -2.0, -3.0, -4.0, -5.0, -6.0 ] );
var y0 = new Float64Array( [ 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 y1 = new Float64Array( y0.buffer, y0.BYTES_PER_ELEMENT*3 ); // start at 4th element
dmap( 3, x1, -2, y1, 1, abs );
// y0 => <Float64Array>[ 0.0, 0.0, 0.0, 6.0, 4.0, 2.0 ]Applies a unary function to a double-precision floating-point strided input array and assigns results to a double-precision floating-point strided output array using alternative indexing semantics.
var Float64Array = require( '@stdlib/array-float64' );
var abs = require( '@stdlib/math-base-special-abs' );
var x = new Float64Array( [ -1.0, -2.0, -3.0, -4.0, -5.0 ] );
var y = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0 ] );
dmap.ndarray( x.length, x, 1, 0, y, 1, 0, abs );
// y => <Float64Array>[ 1.0, 2.0, 3.0, 4.0, 5.0 ]The function accepts the following additional arguments:
- offsetX: starting index for
x. - offsetY: starting index for
y.
While typed array views mandate a view offset based on the underlying buffer, the offsetX and offsetY parameters support indexing semantics based on starting indices. For example, to index every other value in x starting from the second value and to index the last N elements in y in reverse order,
var Float64Array = require( '@stdlib/array-float64' );
var abs = require( '@stdlib/math-base-special-abs' );
var x = new Float64Array( [ -1.0, -2.0, -3.0, -4.0, -5.0, -6.0 ] );
var y = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );
dmap.ndarray( 3, x, 2, 1, y, -1, y.length-1, abs );
// y => <Float64Array>[ 0.0, 0.0, 0.0, 6.0, 4.0, 2.0 ]<!DOCTYPE html>
<html lang="en">
<body>
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/math-base-special-round@umd/browser.js"></script>
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/random-base-randu@umd/browser.js"></script>
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/array-float64@umd/browser.js"></script>
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/strided-base-dmap@umd/browser.js"></script>
<script type="text/javascript">
(function () {
function scale( x ) {
return x * 10.0;
}
var x = new Float64Array( 10 );
var y = new Float64Array( 10 );
var i;
for ( i = 0; i < x.length; i++ ) {
x[ i ] = round( (randu()*200.0) - 100.0 );
}
console.log( x );
console.log( y );
dmap.ndarray( x.length, x, 1, 0, y, -1, y.length-1, scale );
console.log( y );
})();
</script>
</body>
</html>@stdlib/strided-base/smap: apply a unary function to a single-precision floating-point strided input array and assign results to a single-precision floating-point strided output array.@stdlib/strided-base/unary: apply a unary callback to elements in a strided input array and assign results to elements in a strided output array.
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.
See LICENSE.
Copyright © 2016-2025. The Stdlib Authors.
