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zcopy

Copy values from one complex double-precision floating-point vector to another complex double-precision floating-point vector.

Installation

npm install @stdlib/blas-base-zcopy

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

zcopy( N, x, strideX, y, strideY )

Copies values from x into y.

var Complex128Array = require( '@stdlib/array-complex128' );
var real = require( '@stdlib/complex-float64-real' );
var imag = require( '@stdlib/complex-float64-imag' );

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

zcopy( x.length, x, 1, y, 1 );

var z = y.get( 0 );
// returns <Complex128>

var re = real( z );
// returns 1.0

var im = imag( z );
// returns 2.0

The function has the following parameters:

• N: number of indexed elements.
• x: input Complex128Array.
• strideX: index increment for x.
• y: destination Complex128Array.
• strideY: index increment for y.

The N and stride parameters determine how values from x are copied into y. For example, to copy in reverse order every other value in x into the first N elements of y,

var Complex128Array = require( '@stdlib/array-complex128' );
var real = require( '@stdlib/complex-float64-real' );
var imag = require( '@stdlib/complex-float64-imag' );

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

zcopy( 2, x, -2, y, 1 );

var z = y.get( 0 );
// returns <Complex128>

var re = real( z );
// returns 5.0

var im = imag( z );
// returns 6.0

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

var Complex128Array = require( '@stdlib/array-complex128' );
var real = require( '@stdlib/complex-float64-real' );
var imag = require( '@stdlib/complex-float64-imag' );

// Initial arrays...
var x0 = new Complex128Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );
var y0 = new Complex128Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

// Create offset views...
var x1 = new Complex128Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
var y1 = new Complex128Array( y0.buffer, y0.BYTES_PER_ELEMENT*2 ); // start at 3rd element

// Copy in reverse order every other value from `x1` into `y1`...
zcopy( 2, x1, -2, y1, 1 );

var z = y0.get( 2 );
// returns <Complex128>

var re = real( z );
// returns 7.0

var im = imag( z );
// returns 8.0

zcopy.ndarray( N, x, strideX, offsetX, y, strideY, offsetY )

Copies values from x into y using alternative indexing semantics.

var Complex128Array = require( '@stdlib/array-complex128' );
var real = require( '@stdlib/complex-float64-real' );
var imag = require( '@stdlib/complex-float64-imag' );

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

zcopy.ndarray( x.length, x, 1, 0, y, 1, 0 );

var z = y.get( 0 );
// returns <Complex128>

var re = real( z );
// returns 1.0

var im = imag( z );
// returns 2.0

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 copy every other value in x starting from the second value into the last N elements in y where x[i] = y[n], x[i+2] = y[n-1],...,

var Complex128Array = require( '@stdlib/array-complex128' );
var real = require( '@stdlib/complex-float64-real' );
var imag = require( '@stdlib/complex-float64-imag' );

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

zcopy.ndarray( 2, x, 2, 1, y, -1, y.length-1 );

var z = y.get( y.length-1 );
// returns <Complex128>

var re = real( z );
// returns 3.0

var im = imag( z );
// returns 4.0

Notes

• If N <= 0, both functions return y unchanged.
• zcopy() corresponds to the BLAS level 1 function zcopy.

Examples

var discreteUniform = require( '@stdlib/random-base-discrete-uniform' );
var filledarrayBy = require( '@stdlib/array-filled-by' );
var Complex128 = require( '@stdlib/complex-float64-ctor' );
var zcopy = require( '@stdlib/blas-base-zcopy' );

function rand() {
    return new Complex128( discreteUniform( 0, 10 ), discreteUniform( -5, 5 ) );
}

var x = filledarrayBy( 10, 'complex128', rand );
console.log( x.get( 0 ).toString() );

var y = filledarrayBy( 10, 'complex128', rand );
console.log( y.get( 0 ).toString() );

// Copy elements from `x` into `y` starting from the end of `y`:
zcopy( x.length, x, 1, y, -1 );
console.log( y.get( y.length-1 ).toString() );

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C APIs

Usage

#include "stdlib/blas/base/zcopy.h"

c_zcopy( N, *X, strideX, *Y, strideY )

Copies values from X into Y.

const double x[] = { 1.0, 2.0, 3.0, 4.0 }; // interleaved real and imaginary components
double y[] = { 0.0, 0.0, 0.0, 0.0 };

c_zcopy( 2, (void *)x, 1, (void *)y, 1 );

The function accepts the following arguments:

• N: [in] CBLAS_INT number of indexed elements.
• X: [in] void* input array.
• strideX: [in] CBLAS_INT index increment for X.
• Y: [out] void* output array.
• strideY: [in] CBLAS_INT index increment for Y.

void c_zcopy( const CBLAS_INT N, const void *X, const CBLAS_INT strideX, void *Y, const CBLAS_INT strideY );

c_zcopy_ndarray( N, *X, strideX, offsetX, *Y, strideY, offsetY )

Copies values from X into Y using alternative indexing semantics.

const double x[] = { 1.0, 2.0, 3.0, 4.0 }; // interleaved real and imaginary components
double y[] = { 0.0, 0.0, 0.0, 0.0 };

c_zcopy_ndarray( 2, (void *)x, 1, 0, (void *)y, 1, 0 );

The function accepts the following arguments:

• N: [in] CBLAS_INT number of indexed elements.
• X: [in] void* input array.
• strideX: [in] CBLAS_INT index increment for X.
• offsetX: [in] CBLAS_INT starting index for X.
• Y: [out] void* output array.
• strideY: [in] CBLAS_INT index increment for Y.
• offsetY: [in] CBLAS_INT starting index for Y.

void c_zcopy_ndarray( const CBLAS_INT N, const void *X, const CBLAS_INT strideX, const CBLAS_INT offsetX, void *Y, const CBLAS_INT strideY, const CBLAS_INT offsetY );

Examples

#include "stdlib/blas/base/zcopy.h"
#include <stdio.h>

int main( void ) {
    // Create strided arrays:
    const double x[] = { 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 };
    double y[] = { 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 };

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

    // Specify stride lengths:
    const int strideX = 1;
    const int strideY = -1;

    // Copy elements:
    c_zcopy( N, (void *)x, strideX, (void *)y, strideY );

    // Print the result:
    for ( int i = 0; i < N; i++ ) {
        printf( "y[ %i ] = %lf + %lfj\n", i, y[ i*2 ], y[ (i*2)+1 ] );
    }

    // Copy elements using alternative indexing semantics:
    c_zcopy_ndarray( N, (void *)x, -strideX, N-1, (void *)y, strideY, N-1 );

    // Print the result:
    for ( int i = 0; i < N; i++ ) {
        printf( "y[ %i ] = %lf + %lfj\n", i, y[ i*2 ], y[ (i*2)+1 ] );
    }
}

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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

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License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.