cmap

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

Usage

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

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

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

var Complex64Array = require( '@stdlib/array/complex64' );
var real = require( '@stdlib/complex/float64/real' );
var imag = require( '@stdlib/complex/float64/imag' );
var cceilf = require( '@stdlib/math/base/special/cceilf' );

var x = new Complex64Array( [ -2.3, 1.5, 3.1, -5.2, 4.8, 0.0, -1.6, 3.4 ] );
var y = new Complex64Array( x.length );

cmap( x.length, x, 1, y, 1, cceilf );

var v = y.get( 0 );
// returns <Complex64>

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 Complex64Array.
  • strideX: index increment for x.
  • y: output Complex64Array.
  • 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 Complex64Array = require( '@stdlib/array/complex64' );
var real = require( '@stdlib/complex/float64/real' );
var imag = require( '@stdlib/complex/float64/imag' );
var cceilf = require( '@stdlib/math/base/special/cceilf' );

var x = new Complex64Array( [ -2.3, 1.5, 3.1, -5.2, 4.8, 0.0, -1.6, 3.4 ] );
var y = new Complex64Array( x.length );

cmap( 2, x, 2, y, -1, cceilf );

var v = y.get( 0 );
// returns <Complex64>

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 Complex64Array = require( '@stdlib/array/complex64' );
var real = require( '@stdlib/complex/float64/real' );
var imag = require( '@stdlib/complex/float64/imag' );
var cceilf = require( '@stdlib/math/base/special/cceilf' );

// Initial arrays...
var x0 = new Complex64Array( [ -2.3, 1.5, 3.1, -5.2, 4.8, 0.0, -1.6, 3.4 ] );
var y0 = new Complex64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

// Create offset views...
var x1 = new Complex64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
var y1 = new Complex64Array( y0.buffer, y0.BYTES_PER_ELEMENT*2 ); // start at 3rd element

cmap( 2, x1, -2, y1, 1, cceilf );

var v = y0.get( 2 );
// returns <Complex64>

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

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

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

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

var Complex64Array = require( '@stdlib/array/complex64' );
var real = require( '@stdlib/complex/float64/real' );
var imag = require( '@stdlib/complex/float64/imag' );
var cceilf = require( '@stdlib/math/base/special/cceilf' );

var x = new Complex64Array( [ -2.3, 1.5, 3.1, -5.2, 4.8, 0.0, -1.6, 3.4 ] );
var y = new Complex64Array( x.length );

cmap.ndarray( x.length, x, 1, 0, y, 1, 0, cceilf );

var v = y.get( 0 );
// returns <Complex64>

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 Complex64Array = require( '@stdlib/array/complex64' );
var real = require( '@stdlib/complex/float64/real' );
var imag = require( '@stdlib/complex/float64/imag' );
var cceilf = require( '@stdlib/math/base/special/cceilf' );

var x = new Complex64Array( [ -2.3, 1.5, 3.1, -5.2, 4.8, 0.0, -1.6, 3.4 ] );
var y = new Complex64Array( x.length );

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

var v = y.get( y.length-1 );
// returns <Complex64>

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 Complex64Array = require( '@stdlib/array/complex64' );
var filledarrayBy = require( '@stdlib/array/filled-by' );
var real = require( '@stdlib/complex/float64/real' );
var imag = require( '@stdlib/complex/float64/imag' );
var Complex64 = require( '@stdlib/complex/float32/ctor' );
var cmap = require( '@stdlib/strided/base/cmap' );

function scale( x ) {
    var re = real( x );
    var im = imag( x );
    return new Complex64( re*10.0, im*10.0 );
}

var xbuf = filledarrayBy( 10*2, 'float32', discreteUniform( -100.0, 100.0 ) );
var x = new Complex64Array( xbuf.buffer );
console.log( x );

var y = new Complex64Array( x.length );
console.log( y );

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

C APIs

Usage

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

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

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

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

static float complex scale( const float complex x ) {
    float re = crealf( x );
    float im = cimagf( x );
    return ( re+10.0f ) + ( im+10.0f )*I;
}

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

int64_t N = 6;

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

The function accepts the following arguments:

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

Examples

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

// Define a callback:
static float complex scale( const float complex x ) {
    float re = crealf( x );
    float im = cimagf( x );
    return ( re+10.0f ) + ( im+10.0f )*I;
}

int main( void ) {
    // Create an input strided array:
    float 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:
    float 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_cmap( N, X, strideX, Y, strideY, scale );

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

See Also

  • @stdlib/strided/base/zmap: apply a unary function to a double-precision complex floating-point strided input array and assign results to a double-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.
Did you find this page helpful?