@stdlib/strided-base-zmap
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zmap

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Apply a unary function to a double-precision floating-point strided input array and assign results to a double-precision floating-point strided output array.

Installation

npm install @stdlib/strided-base-zmap

Usage

var zmap = require( '@stdlib/strided-base-zmap' );

zmap( N, x, strideX, y, strideY, fcn )

Applies a unary function to a double-precision complex floating-point strided input array and assigns results to a double-precision complex floating-point strided output array.

var Complex128Array = require( '@stdlib/array-complex128' );
var real = require( '@stdlib/complex-real' );
var imag = require( '@stdlib/complex-imag' );
var cceil = require( '@stdlib/math-base-special-cceil' );

var x = new Complex128Array( [ -2.3, 1.5, 3.1, -5.2, 4.8, 0.0, -1.6, 3.4 ] );
var y = new Complex128Array( x.length );

zmap( x.length, x, 1, y, 1, cceil );

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

var re = real( v );
// returns -2.0

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

The function accepts the following arguments:

  • N: number of indexed elements.
  • x: input Complex128Array.
  • strideX: index increment for x.
  • y: output Complex128Array.
  • strideY: index increment for y.
  • fcn: function to apply.

The N and stride parameters determine which elements in the strided arrays are accessed at runtime. For example, to index every other value in x and to index the first N elements of y in reverse order,

var Complex128Array = require( '@stdlib/array-complex128' );
var real = require( '@stdlib/complex-real' );
var imag = require( '@stdlib/complex-imag' );
var cceil = require( '@stdlib/math-base-special-cceil' );

var x = new Complex128Array( [ -2.3, 1.5, 3.1, -5.2, 4.8, 0.0, -1.6, 3.4 ] );
var y = new Complex128Array( x.length );

zmap( 2, x, 2, y, -1, cceil );

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

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

var im = imag( v );
// returns 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' );
var real = require( '@stdlib/complex-real' );
var imag = require( '@stdlib/complex-imag' );
var cceil = require( '@stdlib/math-base-special-cceil' );

// Initial arrays...
var x0 = new Complex128Array( [ -2.3, 1.5, 3.1, -5.2, 4.8, 0.0, -1.6, 3.4 ] );
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

zmap( 2, x1, -2, y1, 1, cceil );

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

var re = real( v );
// returns -1.0

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

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

Applies a unary function to a double-precision complex floating-point strided input array and assigns results to a double-precision complex floating-point strided output array using alternative indexing semantics.

var Complex128Array = require( '@stdlib/array-complex128' );
var real = require( '@stdlib/complex-real' );
var imag = require( '@stdlib/complex-imag' );
var cceil = require( '@stdlib/math-base-special-cceil' );

var x = new Complex128Array( [ -2.3, 1.5, 3.1, -5.2, 4.8, 0.0, -1.6, 3.4 ] );
var y = new Complex128Array( x.length );

zmap.ndarray( x.length, x, 1, 0, y, 1, 0, cceil );

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

var re = real( v );
// returns -2.0

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

The function accepts the following additional arguments:

  • 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 index every other value in x starting from the second value and to index the last N elements in y in reverse order,

var Complex128Array = require( '@stdlib/array-complex128' );
var real = require( '@stdlib/complex-real' );
var imag = require( '@stdlib/complex-imag' );
var cceil = require( '@stdlib/math-base-special-cceil' );

var x = new Complex128Array( [ -2.3, 1.5, 3.1, -5.2, 4.8, 0.0, -1.6, 3.4 ] );
var y = new Complex128Array( x.length );

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

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

var re = real( v );
// returns 4.0

var im = imag( v );
// returns -5.0

Examples

var discreteUniform = require( '@stdlib/random-base-discrete-uniform' ).factory;
var Complex128Array = require( '@stdlib/array-complex128' );
var filledarrayBy = require( '@stdlib/array-filled-by' );
var real = require( '@stdlib/complex-real' );
var imag = require( '@stdlib/complex-imag' );
var Complex128 = require( '@stdlib/complex-float64' );
var zmap = require( '@stdlib/strided-base-zmap' );

function scale( x ) {
    var re = real( x );
    var im = imag( x );
    return new Complex128( re*10.0, im*10.0 );
}

var xbuf = filledarrayBy( 10*2, 'float64', discreteUniform( -100.0, 100.0 ) );
var x = new Complex128Array( xbuf.buffer );
console.log( x );

var y = new Complex128Array( x.length );
console.log( y );

zmap.ndarray( x.length, x, 1, 0, y, -1, y.length-1, scale );
console.log( y );

C APIs

Usage

#include "stdlib/strided/base/zmap.h"

stdlib_strided_zmap( N, *X, strideX, *Y, strideY, fcn )

Applies a unary function to a double-precision complex floating-point strided input array and assigns results to a double-precision complex floating-point strided output array.

#include <stdint.h>
#include <complex.h>

static double complex scale( const double complex x ) {
    double re = creal( x );
    double im = cimag( x );
    return ( re+10.0 ) + ( im+10.0 )*I;
}

double complex X[] = { 1.0+1.0*I, 2.0+2.0*I, 3.0+3.0*I, 4.0+4.0*I, 5.0+5.0*I, 6.0+6.0*I };
double complex Y[] = { 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 };

int64_t N = 6;

stdlib_strided_zmap( N, X, 1, Y, 1, scale );

The function accepts the following arguments:

  • N: [in] int64_t number of indexed elements.
  • X: [in] double complex* input array.
  • strideX [in] int64_t index increment for X.
  • Y: [out] double complex* output array.
  • strideY: [in] int64_t index increment for Y.
  • fcn: [in] double complex (*fcn)( double complex ) unary function to apply.
void stdlib_strided_zmap( const int64_t N, const double complex *X, const int64_t strideX, double complex *Y, const int64_t strideY, double complex (*fcn)( double complex ) );

Examples

#include "stdlib/strided/base/zmap.h"
#include <stdint.h>
#include <stdio.h>
#include <inttypes.h>
#include <complex.h>

// Define a callback:
static double complex scale( const double complex x ) {
    double re = creal( x );
    double im = cimag( x );
    return ( re+10.0 ) + ( im+10.0 )*I;
}

int main( void ) {
    // Create an input strided array:
    double complex X[] = { 1.0+1.0*I, 2.0+2.0*I, 3.0+3.0*I, 4.0+4.0*I, 5.0+5.0*I, 6.0+6.0*I };

    // Create an output strided array:
    double complex Y[] = { 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 };

    // Specify the number of elements:
    int64_t N = 6;

    // Define the strides:
    int64_t strideX = 1;
    int64_t strideY = -1;

    // Apply the callback:
    stdlib_strided_zmap( N, X, strideX, Y, strideY, scale );

    // Print the results:
    for ( int64_t i = 0; i < N; i++ ) {
        printf( "Y[ %"PRId64" ] = %lf + %lfi\n", i, creal( Y[i] ), cimag( Y[i] ) );
    }
}

See Also

  • @stdlib/strided-base/cmap: apply a unary function to a single-precision complex floating-point strided input array and assign results to a single-precision complex floating-point strided output array.
  • @stdlib/strided-base/unary: apply a unary callback to elements in a strided input array and assign results to elements in a strided output array.

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.

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License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.

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