csumkbn

Calculate the sum of single-precision complex floating-point strided array elements using an improved Kahan–Babuška algorithm.

Installation

npm install @stdlib/blas-ext-base-csumkbn

Usage

var csumkbn = require( '@stdlib/blas-ext-base-csumkbn' );

csumkbn( N, x, strideX )

Computes the sum of single-precision complex floating-point strided array elements using an improved Kahan–Babuška algorithm.

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

var x = new Complex64Array( [ 1.0, -2.0, 2.0, 3.0 ] );

var v = csumkbn( x.length, x, 1 );
// returns <Complex64>[ 3.0, 1.0 ]

The function has the following parameters:

• N: number of indexed elements.
• x: input Complex64Array.
• strideX: stride length for x.

The N and stride parameters determine which elements in the strided array are accessed at runtime. For example, to compute the sum of every other element:

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

var x = new Complex64Array( [ 1.0, 2.0, 2.0, -7.0, -2.0, 3.0, 4.0, 2.0 ] );

var v = csumkbn( 2, x, 2 );
// returns <Complex64>[ -1.0, 5.0 ]

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

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

var x0 = new Complex64Array( [ 2.0, 1.0, 2.0, -2.0, -2.0, 2.0, 3.0, 4.0 ] );
var x1 = new Complex64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element

var v = csumkbn( 2, x1, 2 );
// returns <Complex64>[ 5.0, 2.0 ]

csumkbn.ndarray( N, x, strideX, offsetX )

Computes the sum of single-precision complex floating-point strided array elements using an improved Kahan–Babuška algorithm and alternative indexing semantics.

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

var x = new Complex64Array( [ 1.0, -2.0, 2.0, 3.0 ] );

var v = csumkbn.ndarray( 2, x, 1, 0 );
// returns <Complex64>[ 3.0, 1.0 ]

The function has the following additional parameters:

• offsetX: 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 calculate the sum of every other element starting from the second element:

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

var x = new Complex64Array( [ 2.0, 1.0, 2.0, -2.0, -2.0, 2.0, 3.0, 4.0 ] );

var v = csumkbn.ndarray( 2, x, 2, 1 );
// returns <Complex64>[ 5.0, 2.0 ]

Notes

• If N <= 0, both functions return 0.0 + 0.0i.

Examples

var discreteUniform = require( '@stdlib/random-array-discrete-uniform' );
var Complex64Array = require( '@stdlib/array-complex64' );
var csumkbn = require( '@stdlib/blas-ext-base-csumkbn' );

var xbuf = discreteUniform( 10, -100, 100, {
    'dtype': 'float32'
});
console.log( xbuf );

var x = new Complex64Array( xbuf );
var v = csumkbn( x.length, x, 1 );
console.log( v );

C APIs

Usage

#include "stdlib/blas/ext/base/csumkbn.h"

stdlib_strided_csumkbn( N, *X, strideX )

Computes the sum of single-precision complex floating-point strided array elements using an improved Kahan–Babuška algorithm.

#include "stdlib/complex/float32/ctor.h"

const stdlib_complex64_t x[] = {
    stdlib_complex64( 1.0f, 2.0f ),
    stdlib_complex64( 3.0f, 4.0f )
};

stdlib_complex64_t v = stdlib_strided_csumkbn( 2, x, 1 );

The function accepts the following arguments:

• N: [in] CBLAS_INT number of indexed elements.
• X: [in] stdlib_complex64_t* input array.
• strideX: [in] CBLAS_INT stride length for X.

stdlib_complex64_t stdlib_strided_csumkbn( const CBLAS_INT N, const stdlib_complex64_t *X, const CBLAS_INT strideX );

stdlib_strided_csumkbn_ndarray( N, *X, strideX, offsetX )

Computes the sum of single-precision complex floating-point strided array elements using an improved Kahan–Babuška algorithm and alternative indexing semantics.

#include "stdlib/complex/float32/ctor.h"

const stdlib_complex64_t x[] = {
    stdlib_complex64( 1.0f, 2.0f ),
    stdlib_complex64( 3.0f, 4.0f )
};

stdlib_complex64_t v = stdlib_strided_csumkbn_ndarray( 2, x, 1, 0 );

The function accepts the following arguments:

• N: [in] CBLAS_INT number of indexed elements.
• X: [in] stdlib_complex64_t* input array.
• strideX: [in] CBLAS_INT stride length for X.
• offsetX: [in] CBLAS_INT starting index for X.

stdlib_complex64_t stdlib_strided_csumkbn_ndarray( const CBLAS_INT N, const stdlib_complex64_t *X, const CBLAS_INT strideX, const CBLAS_INT offsetX );

Examples

#include "stdlib/blas/ext/base/csumkbn.h"
#include "stdlib/complex/float32/ctor.h"
#include "stdlib/complex/float32/real.h"
#include "stdlib/complex/float32/imag.h"
#include <stdio.h>

int main( void ) {
    // Create a strided array:
    const stdlib_complex64_t x[] = {
        stdlib_complex64( 1.0f, 2.0f ),
        stdlib_complex64( 3.0f, 4.0f ),
        stdlib_complex64( 5.0f, 6.0f ),
        stdlib_complex64( 7.0f, 8.0f )
    };

    // Specify the number of elements:
    const int N = 4;

    // Specify the stride length:
    const int strideX = 1;

    // Compute the sum:
    stdlib_complex64_t v = stdlib_strided_csumkbn( N, x, strideX );

    // Print the result:
    printf( "sum: %f + %fi\n", stdlib_complex64_real( v ), stdlib_complex64_imag( v ) );
}

References

• Neumaier, Arnold. 1974. "Rounding Error Analysis of Some Methods for Summing Finite Sums." Zeitschrift Für Angewandte Mathematik Und Mechanik 54 (1): 39–51. doi:10.1002/zamm.19740540106.

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.

Copyright

Copyright © 2016-2026. The Stdlib Authors.