@stdlib/blas-base-wasm-zdrot

v0.1.1

Published

a month ago

Apply a plane rotation.

zdrot

Apply a plane rotation.

Installation

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

Usage

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

zdrot.main( N, zx, strideX, zy, strideY, c, s )

Applies a plane rotation.

var Complex128Array = require( '@stdlib/array-complex128' );

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

zdrot.main( zx.length, zx, 1, zy, 1, 0.8, 0.6 );
// zx => <Complex128Array>[ ~0.8, ~1.6, ~2.4, ~3.2, 4.0, ~4.8, ~5.6, ~6.4 ]
// zy => <Complex128Array>[ ~-0.6, ~-1.2, ~-1.8, ~-2.4, -3.0, ~-3.6, ~-4.2, ~-4.8 ]

The function has the following parameters:

N: number of indexed elements.
zx: first input Complex128Array.
strideX: index increment for zx.
zy: second input Complex128Array.
strideY: index increment for zy.
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 Complex128Array = require( '@stdlib/array-complex128' );

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

zdrot.main( 2, zx, 2, zy, 2, 0.8, 0.6 );
// zx => <Complex128Array>[ ~0.8, ~1.6, 3.0, 4.0, 4.0, ~4.8, 7.0, 8.0 ]
// zy => <Complex128Array>[ ~-0.6, ~-1.2,  0.0, 0.0, -3.0, ~-3.6,  0.0, 0.0 ]

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

var Complex128Array = require( '@stdlib/array-complex128' );

// Initial arrays...
var zx0 = new Complex128Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );
var zy0 = new Complex128Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

// Create offset views...
var zx1 = new Complex128Array( zx0.buffer, zx0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
var zy1 = new Complex128Array( zy0.buffer, zy0.BYTES_PER_ELEMENT*2 ); // start at 3rd element

zdrot.main( 2, zx1, -2, zy1, 1, 0.8, 0.6 );
// zx0 => <Complex128Array>[ 1.0, 2.0, ~2.4, ~3.2, 5.0, 6.0, ~5.6, ~6.4 ]
// zy0 => <Complex128Array>[ 0.0, 0.0,  0.0, 0.0, ~-4.2, ~-4.8, ~-1.8, ~-2.4 ]

zdrot.ndarray( N, zx, strideX, offsetX, zy, strideY, offsetY, c, s )

Applies a plane rotation using alternative indexing semantics.

var Complex128Array = require( '@stdlib/array-complex128' );

var zx = new Complex128Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );
var zy = new Complex128Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

zdrot.ndarray( zx.length, zx, 1, 0, zy, 1, 0, 0.8, 0.6 );
// zx => <Complex128Array>[ ~0.8, ~1.6, ~2.4, ~3.2, 4.0, ~4.8 ]
// zy => <Complex128Array>[ ~-0.6, ~-1.2, ~-1.8, ~-2.4, -3.0, ~-3.6 ]

The function has the following additional parameters:

offsetX: starting index for zx.
offsetY: starting index for zy.

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 Complex128Array = require( '@stdlib/array-complex128' );

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

zdrot.ndarray( 2, zx, 2, 1, zy, 2, 1, 0.8, 0.6 );
// zx => <Complex128Array>[ 1.0, 2.0, ~2.4, ~3.2, 5.0, 6.0, ~5.6, ~6.4 ]
// zy => <Complex128Array>[ 0.0, 0.0, ~-1.8, ~-2.4, 0.0, 0.0, ~-4.2, ~-4.8 ]

Module

zdrot.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 zdrot.Module( mem );
// returns <Module>

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

zdrot.Module.prototype.main( N, zxp, sx, zyp, 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 Complex128Array = require( '@stdlib/array-complex128' );
var reinterpretComplex128 = require( '@stdlib/strided-base-reinterpret-complex128' );
var zdrot = require( '@stdlib/blas-base-wasm-zdrot' );

// 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 zdrot.Module( mem );
// returns <Module>

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

// Define a vector data type:
var dtype = 'complex128';

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

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

// Write vector values to module memory:
var xbuf = oneTo( N*2, 'float64' );
var zx = new Complex128Array( xbuf.buffer );
mod.write( zxptr, zx );

var ybuf = ones( N*2, 'float64' );
var zy = new Complex128Array( ybuf.buffer );
mod.write( zyptr, zy );

// Perform computation:
mod.main( N, zxptr, 1, zyptr, 1, 0.8, 0.6 );

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

console.log( reinterpretComplex128( viewX, 0 ) );
// => <Float64Array>[ ~1.4, ~2.2, 3.0, ~3.8, ~4.6, ~5.4, ~6.2, 7.0, ~7.8, ~8.6 ]

console.log( reinterpretComplex128( viewY, 0 ) );
// => <Float64Array>[ ~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.
zxp: first input Complex128Array pointer (i.e., byte offset).
sx: index increment for zx.
zyp: second input Complex128Array pointer (i.e., byte offset).
sy: index increment for zy.
c: cosine of the angle of rotation.
s: sine of the angle of rotation.

zdrot.Module.prototype.ndarray( N, zxp, sx, ox, zyp, 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 Complex128Array = require( '@stdlib/array-complex128' );
var reinterpretComplex128 = require( '@stdlib/strided-base-reinterpret-complex128' );
var zdrot = require( '@stdlib/blas-base-wasm-zdrot' );

// 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 zdrot.Module( mem );
// returns <Module>

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

// Define a vector data type:
var dtype = 'complex128';

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

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

// Write vector values to module memory:
var xbuf = oneTo( N*2, 'float64' );
var zx = new Complex128Array( xbuf.buffer );
mod.write( zxptr, zx );

var ybuf = ones( N*2, 'float64' );
var zy = new Complex128Array( ybuf.buffer );
mod.write( zyptr, zy );

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

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

console.log( reinterpretComplex128( viewX, 0 ) );
// => <Float64Array>[ ~1.4, ~2.2, 3.0, ~3.8, ~4.6, ~5.4, ~6.2, 7.0, ~7.8, ~8.6 ]

console.log( reinterpretComplex128( viewY, 0 ) );
// => <Float64Array>[ ~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 zx.
oy: starting index for zy.

Notes

If N <= 0, zx and zy are left unchanged.
This package implements routines using WebAssembly. When provided arrays which are not allocated on a zdrot 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/zdrot. 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/zdrot. 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.
zdrot() corresponds to the BLAS level 1 function zdrot.

Examples

var oneTo = require( '@stdlib/array-one-to' );
var ones = require( '@stdlib/array-ones' );
var zeros = require( '@stdlib/array-zeros' );
var Complex128Array = require( '@stdlib/array-complex128' );
var reinterpretComplex128 = require( '@stdlib/strided-base-reinterpret-complex128' );
var zdrot = require( '@stdlib/blas-base-wasm-zdrot' );

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

var xbuf = oneTo( N*2, 'float64' );
var zx = new Complex128Array( xbuf.buffer );

var ybuf = ones( N*2, 'float64' );
var zy = new Complex128Array( ybuf.buffer );

// Perform computation:
zdrot.ndarray( N, zx, 1, 0, zy, 1, 0, 0.8, 0.6 );

// Print the results:
console.log( reinterpretComplex128( zx, 0 ) );
// => <Float64Array>[ ~1.4, ~2.2, 3.0, ~3.8, ~4.6, ~5.4, ~6.2, 7.0, ~7.8, ~8.6 ]

console.log( reinterpretComplex128( zy, 0 ) );
// => <Float64Array>[ ~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.

Community

License

See LICENSE.