@stdlib/strided-base-smap2 NPM

smap2

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

Installation

npm install @stdlib/strided-base-smap2

Usage

var smap2 = require( '@stdlib/strided-base-smap2' );

smap2( N, x, strideX, y, strideY, z, strideZ, fcn )

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

var Float32Array = require( '@stdlib/array-float32' );
var addf = require( '@stdlib/math-base-ops-addf' );

var x = new Float32Array( [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, -3.0 ] );
var y = new Float32Array( [ 2.0, 1.0, 3.0, -2.0, 4.0, 1.0, -1.0, 3.0 ] );
var z = new Float32Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

smap2( x.length, x, 1, y, 1, z, 1, addf );
// z => <Float32Array>[ 0.0, 2.0, 6.0, -7.0, 8.0, 1.0, -2.0, 0.0 ]

The function accepts the following arguments:

N: number of indexed elements.
x: input Float32Array.
strideX: index increment for x.
y: input Float32Array.
strideY: index increment for y.
z: output Float32Array.
strideZ: index increment for z.
fcn: function to apply.

The N and stride parameters determine which strided array elements 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 Float32Array = require( '@stdlib/array-float32' );
var addf = require( '@stdlib/math-base-ops-addf' );

var x = new Float32Array( [ -1.0, -2.0, -3.0, -4.0, -5.0, -6.0 ] );
var y = new Float32Array( [ 1.0, 1.0, 2.0, 2.0, 3.0, 3.0 ] );
var z = new Float32Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

smap2( 3, x, 2, y, -1, z, 1, addf );
// z => <Float32Array>[ 1.0, -2.0, -4.0, 0.0, 0.0, 0.0 ]

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

var Float32Array = require( '@stdlib/array-float32' );
var addf = require( '@stdlib/math-base-ops-addf' );

// Initial arrays...
var x0 = new Float32Array( [ -1.0, -2.0, -3.0, -4.0, -5.0, -6.0 ] );
var y0 = new Float32Array( [ 1.0, 1.0, 2.0, 2.0, 3.0, 3.0 ] );
var z0 = new Float32Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

// Create offset views...
var x1 = new Float32Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
var y1 = new Float32Array( y0.buffer, y0.BYTES_PER_ELEMENT*3 ); // start at 4th element
var z1 = new Float32Array( z0.buffer, z0.BYTES_PER_ELEMENT*2 ); // start at 3rd element

smap2( 3, x1, -2, y1, 1, z1, 1, addf );
// z0 => <Float32Array>[ 0.0, 0.0, -4.0, -1.0, 1.0, 0.0 ]

smap2.ndarray( N, x, strideX, offsetX, y, strideY, offsetY, z, strideZ, offsetZ, fcn )

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

var Float32Array = require( '@stdlib/array-float32' );
var addf = require( '@stdlib/math-base-ops-addf' );

var x = new Float32Array( [ -1.0, -2.0, -3.0, -4.0, -5.0 ] );
var y = new Float32Array( [ 1.0, 1.0, 2.0, 2.0, 3.0 ] );
var z = new Float32Array( [ 0.0, 0.0, 0.0, 0.0, 0.0 ] );

smap2.ndarray( x.length, x, 1, 0, y, 1, 0, z, 1, 0, addf );
// z => <Float32Array>[ 0.0, -1.0, -1.0, -2.0, -2.0 ]

The function accepts the following addfitional arguments:

offsetX: starting index for x.
offsetY: starting index for y.
offsetZ: starting index for z.

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 Float32Array = require( '@stdlib/array-float32' );
var addf = require( '@stdlib/math-base-ops-addf' );

var x = new Float32Array( [ -1.0, -2.0, -3.0, -4.0, -5.0, -6.0 ] );
var y = new Float32Array( [ 1.0, 1.0, 2.0, 2.0, 3.0, 3.0 ] );
var z = new Float32Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );

smap2.ndarray( 3, x, 2, 1, y, -1, y.length-1, z, 1, 3, addf );
// z => <Float32Array>[ 0.0, 0.0, 0.0, 1.0, -1.0, -4.0 ]

Examples

var discreteUniform = require( '@stdlib/random-base-discrete-uniform' ).factory;
var filledarrayBy = require( '@stdlib/array-filled-by' );
var Float32Array = require( '@stdlib/array-float32' );
var addf = require( '@stdlib/math-base-ops-addf' );
var smap2 = require( '@stdlib/strided-base-smap2' );

var x = filledarrayBy( 10, 'float32', discreteUniform( -100, 100 ) );
console.log( x );

var y = filledarrayBy( x.length, 'float32', discreteUniform( -100, 100 ) );
console.log( y );

var z = new Float32Array( x.length );
console.log( z );

smap2.ndarray( x.length, x, 1, 0, y, -1, y.length-1, z, 1, 0, addf );
console.log( z );

C APIs

Usage

#include "stdlib/strided/base/smap2.h"

stdlib_strided_smap2( N, X, strideX, Y, strideY, *Z, strideZ, fcn )

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

#include <stdint.h>

static float addf( const float x, const float y ) {
    return x + y;
}

float X[] = { 1.0f, 2.0f, 3.0f, 4.0f, 5.0f, 6.0f };
float Y[] = { 1.0f, 2.0f, 3.0f, 4.0f, 5.0f, 6.0f };
float Z[] = { 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f };

int64_t N = 6;

stdlib_strided_smap2( N, X, 1, Y, 1, Z, 1, addf );

The function accepts the following arguments:

N: [in] int64_t number of indexed elements.
X: [in] float* input array.
strideX [in] int64_t index increment for X.
Y: [in] float* input array.
strideY: [in] int64_t index increment for Y.
Z: [out] float* output array.
strideZ: [in] int64_t index increment for Z.
fcn: [in] float (*fcn)( float, float ) binary function to apply.

void stdlib_strided_smap2( const int64_t N, const float *X, const int64_t strideX, const float *Y, const int64_t strideY, float *Z, const int64_t strideZ, float (*fcn)( float, float ) );

Examples

#include "stdlib/strided/base/smap2.h"
#include <stdint.h>
#include <stdio.h>
#include <inttypes.h>

// Define a callback:
static float addf( const float x, const float y ) {
    return x + y;
}

int main( void ) {
    // Create input strided arrays:
    float X[] = { 1.0f, 2.0f, 3.0f, 4.0f, 5.0f, 6.0f };
    float Y[] = { 1.0f, 2.0f, 3.0f, 4.0f, 5.0f, 6.0f };

    // Create an output strided array:
    float Z[] = { 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f };

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

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

    // Apply the callback:
    stdlib_strided_smap2( N, X, strideX, Y, strideY, Z, strideZ, addf );

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

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.