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csrot

NPM version Build Status Coverage Status

Apply a plane rotation.

Installation

npm install @stdlib/blas-base-csrot-wasm

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 csrot = require( '@stdlib/blas-base-csrot-wasm' );

csrot.main( N, cx, strideX, cy, strideY, c, s )

Applies a plane rotation.

var Complex64Array = require( '@stdlib/array-complex64' );
var realf = require( '@stdlib/complex-float32-real' );
var imagf = require( '@stdlib/complex-float32-imag' );

var cx = new Complex64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );
var cy = new Complex64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

csrot.main( cx.length, cx, 1, cy, 1, 0.8, 0.6 );

var z = cy.get( 0 );
// returns <Complex64>

var re = realf( z );
// returns ~-0.6

var im = imagf( z );
// returns ~-1.2

z = cx.get( 0 );
// returns <Complex64>

re = realf( z );
// returns ~0.8

im = imagf( z );
// returns ~1.6

The function has the following parameters:

  • N: number of indexed elements.
  • cx: first input Complex64Array.
  • strideX: index increment for cx.
  • cy: second input Complex64Array.
  • strideY: index increment for cy.
  • c: cosine of the angle of rotation.
  • s: sine of the angle of rotation.

The N and stride parameters determine how values in the strided arrays are accessed at runtime. For example, to apply a plane rotation to every other element,

var Complex64Array = require( '@stdlib/array-complex64' );
var realf = require( '@stdlib/complex-float32-real' );
var imagf = require( '@stdlib/complex-float32-imag' );

var cx = new Complex64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );
var cy = new Complex64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

csrot.main( 2, cx, 2, cy, 2, 0.8, 0.6 );

var z = cy.get( 0 );
// returns <Complex64>

var re = realf( z );
// returns ~-0.6

var im = imagf( z );
// returns ~-1.2

z = cx.get( 0 );
// returns <Complex64>

re = realf( z );
// returns ~0.8

im = imagf( z );
// returns ~1.6

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

var Complex64Array = require( '@stdlib/array-complex64' );
var realf = require( '@stdlib/complex-float32-real' );
var imagf = require( '@stdlib/complex-float32-imag' );

// Initial arrays...
var cx0 = new Complex64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );
var cy0 = new Complex64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

// Create offset views...
var cx1 = new Complex64Array( cx0.buffer, cx0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
var cy1 = new Complex64Array( cy0.buffer, cy0.BYTES_PER_ELEMENT*2 ); // start at 3rd element

csrot.main( 2, cx1, -2, cy1, 1, 0.8, 0.6 );

var z = cy0.get( 2 );
// returns <Complex64>

var re = realf( z );
// returns ~-4.2

var im = imagf( z );
// returns ~-4.8

z = cx0.get( 3 );
// returns <Complex64>

re = realf( z );
// returns ~5.6

im = imagf( z );
// returns ~6.4

csrot.ndarray( N, cx, strideX, offsetX, cy, strideY, offsetY, c, s )

Applies a plane rotation using alternative indexing semantics.

var Complex64Array = require( '@stdlib/array-complex64' );
var realf = require( '@stdlib/complex-float32-real' );
var imagf = require( '@stdlib/complex-float32-imag' );

var cx = new Complex64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );
var cy = new Complex64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

csrot.ndarray( cx.length, cx, 1, 0, cy, 1, 0, 0.8, 0.6 );

var z = cy.get( 0 );
// returns <Complex64>

var re = realf( z );
// returns ~-0.6

var im = imagf( z );
// returns ~-1.2

z = cx.get( 0 );
// returns <Complex64>

re = realf( z );
// returns ~0.8

im = imagf( z );
// returns ~1.6

The function has the following additional parameters:

  • offsetX: starting index for cx.
  • offsetY: starting index for cy.

While typed array views mandate a view offset based on the underlying buffer, the offset parameters support indexing semantics based on starting indices. For example, to apply a plane rotation to every other element starting from the second element,

var Complex64Array = require( '@stdlib/array-complex64' );
var realf = require( '@stdlib/complex-float32-real' );
var imagf = require( '@stdlib/complex-float32-imag' );

var cx = new Complex64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );
var cy = new Complex64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

csrot.ndarray( 2, cx, 2, 1, cy, 2, 1, 0.8, 0.6 );

var z = cy.get( 3 );
// returns <Complex64>

var re = realf( z );
// returns ~-4.2

var im = imagf( z );
// returns ~-4.8

z = cx.get( 1 );
// returns <Complex64>

re = realf( z );
// returns ~2.4

im = imagf( z );
// returns ~3.2

Module

csrot.Module( memory )

Returns a new WebAssembly module wrapper instance which uses the provided WebAssembly memory instance as its underlying memory.

var Memory = require( '@stdlib/wasm-memory' );

// Create a new memory instance with an initial size of 10 pages (640KiB) and a maximum size of 100 pages (6.4MiB):
var mem = new Memory({
    'initial': 10,
    'maximum': 100
});

// Create a BLAS routine:
var mod = new csrot.Module( mem );
// returns <Module>

// Initialize the routine:
mod.initializeSync();

csrot.Module.prototype.main( N, cxp, sx, cyp, sy, c, s )

Applies a plane rotation.

var Memory = require( '@stdlib/wasm-memory' );
var oneTo = require( '@stdlib/array-one-to' );
var ones = require( '@stdlib/array-ones' );
var zeros = require( '@stdlib/array-zeros' );
var bytesPerElement = require( '@stdlib/ndarray-base-bytes-per-element' );
var Complex64Array = require( '@stdlib/array-complex64' );
var reinterpretComplex64 = require( '@stdlib/strided-base-reinterpret-complex64' );
var csrot = require( '@stdlib/blas-base-csrot-wasm' );

// Create a new memory instance with an initial size of 10 pages (320KiB) and a maximum size of 100 pages (6.4MiB):
var mem = new Memory({
    'initial': 10,
    'maximum': 100
});

// Create a BLAS routine:
var mod = new csrot.Module( mem );
// returns <Module>

// Initialize the routine:
mod.initializeSync();

// Define a vector data type:
var dtype = 'complex64';

// Specify a vector length:
var N = 5;

// Define pointers (i.e., byte offsets) for storing the input vectors:
var cxptr = 0;
var cyptr = N * bytesPerElement( dtype );

// Write vector values to module memory:
var xbuf = oneTo( N*2, 'float32' );
var cx = new Complex64Array( xbuf.buffer );
mod.write( cxptr, cx );

var ybuf = ones( N*2, 'float32' );
var cy = new Complex64Array( ybuf.buffer );
mod.write( cyptr, cy );

// Perform computation:
mod.main( N, cxptr, 1, cyptr, 1, 0.8, 0.6 );

// Read out the results:
var viewX = zeros( N, dtype );
var viewY = zeros( N, dtype );
mod.read( cxptr, viewX );
mod.read( cyptr, viewY );

console.log( reinterpretComplex64( viewX, 0 ) );
// => <Float32Array>[ ~1.4, ~2.2, 3.0, ~3.8, ~4.6, ~5.4, ~6.2, 7.0, ~7.8, ~8.6 ]

console.log( reinterpretComplex64( viewY, 0 ) );
// => <Float32Array>[ ~0.2, ~-0.4, -1.0, ~-1.6, ~-2.2, ~-2.8, ~-3.4, -4.0, ~-4.6, ~-5.2 ]

The function has the following parameters:

  • N: number of indexed elements.
  • cxp: first input Complex64Array pointer (i.e., byte offset).
  • sx: index increment for cx.
  • cyp: second input Complex64Array pointer (i.e., byte offset).
  • sy: index increment for cy.
  • c: cosine of the angle of rotation.
  • s: sine of the angle of rotation.

csrot.Module.prototype.ndarray( N, cxp, sx, ox, cyp, sy, oy, c, s )

Applies a plane rotation using alternative indexing semantics.

var Memory = require( '@stdlib/wasm-memory' );
var oneTo = require( '@stdlib/array-one-to' );
var ones = require( '@stdlib/array-ones' );
var zeros = require( '@stdlib/array-zeros' );
var bytesPerElement = require( '@stdlib/ndarray-base-bytes-per-element' );
var Complex64Array = require( '@stdlib/array-complex64' );
var reinterpretComplex64 = require( '@stdlib/strided-base-reinterpret-complex64' );
var csrot = require( '@stdlib/blas-base-csrot-wasm' );

// Create a new memory instance with an initial size of 10 pages (320KiB) and a maximum size of 100 pages (6.4MiB):
var mem = new Memory({
    'initial': 10,
    'maximum': 100
});

// Create a BLAS routine:
var mod = new csrot.Module( mem );
// returns <Module>

// Initialize the routine:
mod.initializeSync();

// Define a vector data type:
var dtype = 'complex64';

// Specify a vector length:
var N = 5;

// Define pointers (i.e., byte offsets) for storing input vectors:
var cxptr = 0;
var cyptr = N * bytesPerElement( dtype );

// Write vector values to module memory:
var xbuf = oneTo( N*2, 'float32' );
var cx = new Complex64Array( xbuf.buffer );
mod.write( cxptr, cx );

var ybuf = ones( N*2, 'float32' );
var cy = new Complex64Array( ybuf.buffer );
mod.write( cyptr, cy );

// Perform computation:
mod.ndarray( N, cxptr, 1, 0, cyptr, 1, 0, 0.8, 0.6 );

// Read out the results:
var viewX = zeros( N, dtype );
var viewY = zeros( N, dtype );
mod.read( cxptr, viewX );
mod.read( cyptr, viewY );

console.log( reinterpretComplex64( viewX, 0 ) );
// => <Float32Array>[ ~1.4, ~2.2, 3.0, ~3.8, ~4.6, ~5.4, ~6.2, 7.0, ~7.8, ~8.6 ]

console.log( reinterpretComplex64( viewY, 0 ) );
// => <Float32Array>[ ~0.2, ~-0.4, -1.0, ~-1.6, ~-2.2, ~-2.8, ~-3.4, -4.0, ~-4.6, ~-5.2 ]

The function has the following additional parameters:

  • ox: starting index for cx.
  • oy: starting index for cy.

Notes

  • If N <= 0, cx and cy are left unchanged.
  • This package implements routines using WebAssembly. When provided arrays which are not allocated on a csrot module memory instance, data must be explicitly copied to module memory prior to computation. Data movement may entail a performance cost, and, thus, if you are using arrays external to module memory, you should prefer using @stdlib/blas-base/csrot. However, if working with arrays which are allocated and explicitly managed on module memory, you can achieve better performance when compared to the pure JavaScript implementations found in @stdlib/blas/base/csrot. Beware that such performance gains may come at the cost of additional complexity when having to perform manual memory management. Choosing between implementations depends heavily on the particular needs and constraints of your application, with no one choice universally better than the other.
  • csrot() corresponds to the BLAS level 1 function csrot.

Examples

var hasWebAssemblySupport = require( '@stdlib/assert-has-wasm-support' );
var oneTo = require( '@stdlib/array-one-to' );
var ones = require( '@stdlib/array-ones' );
var zeros = require( '@stdlib/array-zeros' );
var Complex64Array = require( '@stdlib/array-complex64' );
var reinterpretComplex64 = require( '@stdlib/strided-base-reinterpret-complex64' );
var csrot = require( '@stdlib/blas-base-csrot-wasm' );

// Specify a vector length:
var N = 5;

var xbuf = oneTo( N*2, 'float32' );
var cx = new Complex64Array( xbuf.buffer );

var ybuf = ones( N*2, 'float32' );
var cy = new Complex64Array( ybuf.buffer );

// Perform computation:
csrot.ndarray( N, cx, 1, 0, cy, 1, 0, 0.8, 0.6 );

// Print the results:
console.log( reinterpretComplex64( cx, 0 ) );
// => <Float32Array>[ ~1.4, ~2.2, 3.0, ~3.8, ~4.6, ~5.4, ~6.2, 7.0, ~7.8, ~8.6 ]

console.log( reinterpretComplex64( cy, 0 ) );
// => <Float32Array>[ ~0.2, ~-0.4, -1.0, ~-1.6, ~-2.2, ~-2.8, ~-3.4, -4.0, ~-4.6, ~-5.2 ]

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.

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Apply a plane rotation.

github.com/stdlib-js/stdlib

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nodejs javascript node algebra math vector array stdlib mathematics subroutines linear complex blas ndarray node-js typed rotation level-1 complex64 csrot

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