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About stdlib...

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The library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases.

When you use stdlib, you can be absolutely certain that you are using the most thorough, rigorous, well-written, studied, documented, tested, measured, and high-quality code out there.

To join us in bringing numerical computing to the web, get started by checking us out on GitHub, and please consider financially supporting stdlib. We greatly appreciate your continued support!

zscal

NPM version Build Status Coverage Status

Scales a double-precision complex floating-point vector by a double-precision complex floating-point constant.

Usage

To use in Observable,

zscal = require( 'https://cdn.jsdelivr.net/gh/stdlib-js/blas-base-zscal@umd/browser.js' )

To vendor stdlib functionality and avoid installing dependency trees for Node.js, you can use the UMD server build:

var zscal = require( 'path/to/vendor/umd/blas-base-zscal/index.js' )

To include the bundle in a webpage,

<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/blas-base-zscal@umd/browser.js"></script>

If no recognized module system is present, access bundle contents via the global scope:

<script type="text/javascript">
(function () {
    window.zscal;
})();
</script>

zscal( N, za, zx, strideX )

Scales values from zx by za.

var Complex128Array = require( '@stdlib/array-complex128' );
var Complex128 = require( '@stdlib/complex-float64-ctor' );
var real = require( '@stdlib/complex-float64-real' );
var imag = require( '@stdlib/complex-float64-imag' );

var zx = new Complex128Array( [ 1.0, 1.0, 1.0, 1.0, 1.0, 1.0 ] );
var za = new Complex128( 2.0, 0.0 );

zscal( 3, za, zx, 1 );

var z = zx.get( 0 );
// returns <Complex128>

var re = real( z );
// returns 2.0

var im = imag( z );
// returns 2.0

The function has the following parameters:

The N and stride parameters determine how values from zx are scaled by za. For example, to scale every other value in zx by za,

var Complex128Array = require( '@stdlib/array-complex128' );
var Complex128 = require( '@stdlib/complex-float64-ctor' );
var real = require( '@stdlib/complex-float64-real' );
var imag = require( '@stdlib/complex-float64-imag' );

var zx = new Complex128Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );
var za = new Complex128( 2.0, 0.0 );

zscal( 2, za, zx, 2 );

var z = zx.get( 2 );
// returns <Complex128>

var re = real( z );
// returns 10.0

var im = imag( z );
// returns 12.0

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

var Complex128Array = require( '@stdlib/array-complex128' );
var Complex128 = require( '@stdlib/complex-float64-ctor' );
var real = require( '@stdlib/complex-float64-real' );
var imag = require( '@stdlib/complex-float64-imag' );

// Initial array:
var zx0 = new Complex128Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );

// Define a scalar constant:
var za = new Complex128( 2.0, 2.0 );

// Create an offset view:
var zx1 = new Complex128Array( zx0.buffer, zx0.BYTES_PER_ELEMENT*1 ); // start at 2nd element

// Scales every other value from `zx1` by `za`...
zscal( 3, za, zx1, 1 );

var z = zx0.get( 1 );
// returns <Complex128>

var re = real( z );
// returns -2.0

var im = imag( z );
// returns 14.0

zscal.ndarray( N, za, zx, strideX, offsetX )

Scales values from zx by za using alternative indexing semantics.

var Complex128Array = require( '@stdlib/array-complex128' );
var Complex128 = require( '@stdlib/complex-float64-ctor' );
var real = require( '@stdlib/complex-float64-real' );
var imag = require( '@stdlib/complex-float64-imag' );

var zx = new Complex128Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );
var za = new Complex128( 2.0, 2.0 );

zscal.ndarray( 3, za, zx, 1, 0 );

var z = zx.get( 0 );
// returns <Complex128>

var re = real( z );
// returns -2.0

var im = imag( z );
// returns 6.0

The function has the following additional parameters:

  • offsetX: starting index for zx.

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 scale every other value in the input strided array starting from the second element,

var Complex128Array = require( '@stdlib/array-complex128' );
var Complex128 = require( '@stdlib/complex-float64-ctor' );
var real = require( '@stdlib/complex-float64-real' );
var imag = require( '@stdlib/complex-float64-imag' );

var zx = new Complex128Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );
var za = new Complex128( 2.0, 2.0 );

zscal.ndarray( 2, za, zx, 2, 1 );

var z = zx.get( 3 );
// returns <Complex128>

var re = real( z );
// returns -2.0

var im = imag( z );
// returns 30.0

Notes

  • If N <= 0 or strideX <= 0 , both functions return zx unchanged.
  • zscal() corresponds to the BLAS level 1 function zscal.

Examples

<!DOCTYPE html>
<html lang="en">
<body>
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/random-base-discrete-uniform@umd/browser.js"></script>
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/array-filled-by@umd/browser.js"></script>
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/complex-float64-ctor@umd/browser.js"></script>
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/blas-base-zscal@umd/browser.js"></script>
<script type="text/javascript">
(function () {

function rand() {
    return new Complex128( discreteUniform( 0, 10 ), discreteUniform( -5, 5 ) );
}

var zx = filledarrayBy( 10, 'complex128', rand );
console.log( zx.toString() );

var za = new Complex128( 2.0, 2.0 );
console.log( za.toString() );

// Scales elements from `zx` by `za`:
zscal( zx.length, za, zx, 1 );
console.log( zx.get( zx.length-1 ).toString() );

})();
</script>
</body>
</html>

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.

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License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.