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About stdlib...

We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.

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!

scnrm2

NPM version Build Status Coverage Status

Compute the L2-norm of a complex single-precision floating-point vector.

Usage

To use in Observable,

scnrm2 = require( 'https://cdn.jsdelivr.net/gh/stdlib-js/blas-base-scnrm2@umd/browser.js' )

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

var scnrm2 = require( 'path/to/vendor/umd/blas-base-scnrm2/index.js' )

To include the bundle in a webpage,

<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/blas-base-scnrm2@umd/browser.js"></script>

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

<script type="text/javascript">
(function () {
    window.scnrm2;
})();
</script>

scnrm2( N, cx, strideX )

Computes the L2-norm of a complex single-precision floating-point vector.

var Complex64Array = require( '@stdlib/array-complex64' );

var cx = new Complex64Array( [ 0.3, 0.1, 0.5, 0.0, 0.0, 0.5, 0.0, 0.2 ] );

var norm = scnrm2( 4, cx, 1 );
// returns ~0.8

The function has the following parameters:

  • N: number of indexed elements.
  • cx: input Complex64Array.
  • strideX: index increment for cx.

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

var Complex64Array = require( '@stdlib/array-complex64' );

var cx = new Complex64Array( [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, -3.0 ] );

var norm = scnrm2( 2, cx, 2 );
// returns ~4.6

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

var Complex64Array = require( '@stdlib/array-complex64' );

// Initial array:
var cx0 = new Complex64Array( [ 1.0, -2.0, 3.0, -4.0, 5.0, -6.0 ] );

// Create an offset view:
var cx1 = new Complex64Array( cx0.buffer, cx0.BYTES_PER_ELEMENT*1 ); // start at 2nd element

// Compute the L2-norm:
var norm = scnrm2( 2, cx1, 1 );
// returns ~9.3

scnrm2.ndarray( N, cx, strideX, offset )

Computes the L2-norm of a complex single-precision floating-point vector using alternative indexing semantics.

var Complex64Array = require( '@stdlib/array-complex64' );

var cx = new Complex64Array( [ 0.3, 0.1, 0.5, 0.0, 0.0, 0.5, 0.0, 0.2 ] );

var norm = scnrm2.ndarray( 4, cx, 1, 0 );
// returns ~0.8

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 start from the second index,

var Complex64Array = require( '@stdlib/array-complex64' );

var cx = new Complex64Array( [ 1.0, -2.0, 3.0, -4.0, 5.0, -6.0 ] );

var norm = scnrm2.ndarray( 2, cx, 1, 1 );
// returns ~9.3

Notes

  • If N <= 0, both functions return 0.0.
  • scnrm2() corresponds to the BLAS level 1 function scnrm2.

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-float32-ctor@umd/browser.js"></script>
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/blas-base-scnrm2@umd/browser.js"></script>
<script type="text/javascript">
(function () {

function rand() {
    return new Complex64( discreteUniform( 0, 10 ), discreteUniform( -5, 5 ) );
}

var cx = filledarrayBy( 10, 'complex64', rand );
console.log( cx.toString() );

// Compute the L2-norm:
var norm = scnrm2( cx.length, cx, 1 );
console.log( norm );

})();
</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.