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Add a constant to each single-precision floating-point strided array element and compute the sum using a second-order iterative Kahan–Babuška algorithm.
npm install @stdlib/blas-ext-base-sapxsumkbn2Alternatively,
- To load the package in a website via a
scripttag without installation and bundlers, use the ES Module available on theesmbranch (see README). - If you are using Deno, visit the
denobranch (see README for usage intructions). - For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the
umdbranch (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.
var sapxsumkbn2 = require( '@stdlib/blas-ext-base-sapxsumkbn2' );Adds a constant to each single-precision floating-point strided array element and computes the sum using a second-order iterative Kahan–Babuška algorithm.
var Float32Array = require( '@stdlib/array-float32' );
var x = new Float32Array( [ 1.0, -2.0, 2.0 ] );
var N = x.length;
var v = sapxsumkbn2( N, 5.0, x, 1 );
// returns 16.0The function has the following parameters:
- N: number of indexed elements.
- x: input
Float32Array. - stride: index increment for
x.
The N and stride parameters determine which elements in x are accessed at runtime. For example, to access every other element in x,
var Float32Array = require( '@stdlib/array-float32' );
var floor = require( '@stdlib/math-base-special-floor' );
var x = new Float32Array( [ 1.0, 2.0, 2.0, -7.0, -2.0, 3.0, 4.0, 2.0 ] );
var N = floor( x.length / 2 );
var v = sapxsumkbn2( N, 5.0, x, 2 );
// returns 25.0Note that indexing is relative to the first index. To introduce an offset, use typed array views.
var Float32Array = require( '@stdlib/array-float32' );
var floor = require( '@stdlib/math-base-special-floor' );
var x0 = new Float32Array( [ 2.0, 1.0, 2.0, -2.0, -2.0, 2.0, 3.0, 4.0 ] );
var x1 = new Float32Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
var N = floor( x0.length / 2 );
var v = sapxsumkbn2( N, 5.0, x1, 2 );
// returns 25.0Adds a constant to each single-precision floating-point strided array element and computes the sum using a second-order iterative Kahan–Babuška algorithm and alternative indexing semantics.
var Float32Array = require( '@stdlib/array-float32' );
var x = new Float32Array( [ 1.0, -2.0, 2.0 ] );
var N = x.length;
var v = sapxsumkbn2.ndarray( N, 5.0, x, 1, 0 );
// returns 16.0The function has the following additional parameters:
- offset: starting index for
x.
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 access every other value in x starting from the second value
var Float32Array = require( '@stdlib/array-float32' );
var floor = require( '@stdlib/math-base-special-floor' );
var x = new Float32Array( [ 2.0, 1.0, 2.0, -2.0, -2.0, 2.0, 3.0, 4.0 ] );
var N = floor( x.length / 2 );
var v = sapxsumkbn2.ndarray( N, 5.0, x, 2, 1 );
// returns 25.0- If
N <= 0, both functions return0.0.
var randu = require( '@stdlib/random-base-randu' );
var round = require( '@stdlib/math-base-special-round' );
var Float32Array = require( '@stdlib/array-float32' );
var sapxsumkbn2 = require( '@stdlib/blas-ext-base-sapxsumkbn2' );
var x;
var i;
x = new Float32Array( 10 );
for ( i = 0; i < x.length; i++ ) {
x[ i ] = round( randu()*100.0 );
}
console.log( x );
var v = sapxsumkbn2( x.length, 5.0, x, 1 );
console.log( v );- Klein, Andreas. 2005. "A Generalized Kahan-Babuška-Summation-Algorithm." Computing 76 (3): 279–93. doi:10.1007/s00607-005-0139-x.
@stdlib/blas-ext/base/dapxsumkbn2: adds a constant to each double-precision floating-point strided array element and computes the sum using a second-order iterative Kahan–Babuška algorithm.@stdlib/blas-ext/base/gapxsumkbn2: adds a constant to each strided array element and computes the sum using a second-order iterative Kahan–Babuška algorithm.@stdlib/blas-ext/base/sapxsum: adds a constant to each single-precision floating-point strided array element and computes the sum.@stdlib/blas-ext/base/ssumkbn2: calculate the sum of single-precision floating-point strided array elements using a second-order iterative Kahan–Babuška algorithm.
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.
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