zmap

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.

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/float64/real' );
var imag = require( '@stdlib/complex/float64/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/float64/real' );
var imag = require( '@stdlib/complex/float64/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/float64/real' );
var imag = require( '@stdlib/complex/float64/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/float64/real' );
var imag = require( '@stdlib/complex/float64/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/float64/real' );
var imag = require( '@stdlib/complex/float64/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/float64/real' );
var imag = require( '@stdlib/complex/float64/imag' );
var Complex128 = require( '@stdlib/complex/float64/ctor' );
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.
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