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Apply a plane rotation.
This BLAS level 1 routine applies a real plane rotation to real single-precision floating-point vectors. The plane rotation is applied to N
points, where the points to be rotated are contained in vectors x
and y
and where the cosine and sine of the angle of rotation are c
and s
, respectively. The operation is as follows:
where x_i
and y_i
are the individual elements on which the rotation is applied.
To use in Observable,
srot = require( 'https://cdn.jsdelivr.net/gh/stdlib-js/blas-base-srot@umd/browser.js' )
To vendor stdlib functionality and avoid installing dependency trees for Node.js, you can use the UMD server build:
var srot = require( 'path/to/vendor/umd/blas-base-srot/index.js' )
To include the bundle in a webpage,
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/blas-base-srot@umd/browser.js"></script>
If no recognized module system is present, access bundle contents via the global scope:
<script type="text/javascript">
(function () {
window.srot;
})();
</script>
Applies a plane rotation.
var Float32Array = require( '@stdlib/array-float32' );
var x = new Float32Array( [ 1.0, 2.0, 3.0, 4.0, 5.0 ] );
var y = new Float32Array( [ 6.0, 7.0, 8.0, 9.0, 10.0 ] );
srot( x.length, x, 1, y, 1, 0.8, 0.6 );
// x => <Float32Array>[ ~4.4, ~5.8, ~7.2, ~8.6, 10.0 ]
// y => <Float32Array>[ ~4.2, ~4.4, ~4.6, ~4.8, 5.0 ]
The function has the following parameters:
- N: number of indexed elements.
- x: first input
Float32Array
. - strideX: index increment for
x
. - y: second input
Float32Array
. - strideY: index increment for
y
. - 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 Float32Array = require( '@stdlib/array-float32' );
var x = new Float32Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );
var y = new Float32Array( [ 7.0, 8.0, 9.0, 10.0, 11.0, 12.0 ] );
srot( 3, x, 2, y, 2, 0.8, 0.6 );
// x => <Float32Array>[ ~5.0, 2.0, ~7.8, 4.0, ~10.6, 6.0 ]
// y => <Float32Array>[ 5.0, 8.0, ~5.4, 10.0, ~5.8, 12.0 ]
Note that indexing is relative to the first index. To introduce an offset, use typed array
views.
var Float32Array = require( '@stdlib/array-float32' );
// Initial arrays...
var x0 = new Float32Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );
var y0 = new Float32Array( [ 7.0, 8.0, 9.0, 10.0, 11.0, 12.0 ] );
// Create offset views...
var x1 = new Float32Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
var y1 = new Float32Array( y0.buffer, y0.BYTES_PER_ELEMENT*3 ); // start at 4th element
srot( 3, x1, 1, y1, 1, 0.8, 0.6 );
// x0 => <Float32Array>[ 1.0, ~7.6, 9.0, ~10.4, 5.0, 6.0 ]
// y0 => <Float32Array>[ 7.0, 8.0, 9.0, ~6.8, 7.0, ~7.2 ]
Applies a plane rotation using alternative indexing semantics.
var Float32Array = require( '@stdlib/array-float32' );
var x = new Float32Array( [ 1.0, 2.0, 3.0, 4.0, 5.0 ] );
var y = new Float32Array( [ 6.0, 7.0, 8.0, 9.0, 10.0 ] );
srot.ndarray( 4, x, 1, 1, y, 1, 1, 0.8, 0.6 );
// x => <Float32Array>[ 1.0, ~5.8, ~7.2, ~8.6, 10.0 ]
// y => <Float32Array>[ 6.0, ~4.4, ~4.6, ~4.8, 5.0 ]
The function has the following additional parameters:
- offsetX: starting index for
x
. - offsetY: starting index for
y
.
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 third element,...,
var Float32Array = require( '@stdlib/array-float32' );
var x = new Float32Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );
var y = new Float32Array( [ 7.0, 8.0, 9.0, 10.0, 11.0, 12.0 ] );
srot.ndarray( 2, x, 2, 2, y, 2, 2, 0.8, 0.6 );
// x => <Float32Array>[ 1.0, 2.0, ~7.8, 4.0, ~10.6, 6.0 ]
// y => <Float32Array>[ 7.0, 8.0, ~5.4, 10.0, ~5.8, 12.0 ]
<!DOCTYPE html>
<html lang="en">
<body>
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/random-array-discrete-uniform@umd/browser.js"></script>
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/blas-base-srot@umd/browser.js"></script>
<script type="text/javascript">
(function () {
var opts = {
'dtype': 'float32'
};
var x = discreteUniform( 10, 0, 500, opts );
console.log( x );
var y = discreteUniform( x.length, 0, 255, opts );
console.log( y );
// Applies a plane rotation :
srot( x.length, x, 1, y, 1, 0.8, 0.6 );
console.log( x );
console.log( y );
})();
</script>
</body>
</html>
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 © 2016-2024. The Stdlib Authors.