dmap2
Apply a binary function to double-precision floating-point strided input arrays and assign results to a double-precision floating-point strided output array.
Usage
var dmap2 = require( '@stdlib/strided/base/dmap2' );
dmap2( N, x, strideX, y, strideY, z, strideZ, fcn )
Applies a binary function to double-precision floating-point strided input arrays and assigns results to a double-precision floating-point strided output array.
var Float64Array = require( '@stdlib/array/float64' );
var add = require( '@stdlib/math/base/ops/add' );
var x = new Float64Array( [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, -3.0 ] );
var y = new Float64Array( [ 2.0, 1.0, 3.0, -2.0, 4.0, 1.0, -1.0, 3.0 ] );
var z = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );
dmap2( x.length, x, 1, y, 1, z, 1, add );
// z => <Float64Array>[ 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
Float64Array. - strideX: index increment for
x. - y: input
Float64Array. - strideY: index increment for
y. - z: output
Float64Array. - 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 Float64Array = require( '@stdlib/array/float64' );
var add = require( '@stdlib/math/base/ops/add' );
var x = new Float64Array( [ -1.0, -2.0, -3.0, -4.0, -5.0, -6.0 ] );
var y = new Float64Array( [ 1.0, 1.0, 2.0, 2.0, 3.0, 3.0 ] );
var z = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );
dmap2( 3, x, 2, y, -1, z, 1, add );
// z => <Float64Array>[ 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 Float64Array = require( '@stdlib/array/float64' );
var add = require( '@stdlib/math/base/ops/add' );
// Initial arrays...
var x0 = new Float64Array( [ -1.0, -2.0, -3.0, -4.0, -5.0, -6.0 ] );
var y0 = new Float64Array( [ 1.0, 1.0, 2.0, 2.0, 3.0, 3.0 ] );
var z0 = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );
// Create offset views...
var x1 = new Float64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
var y1 = new Float64Array( y0.buffer, y0.BYTES_PER_ELEMENT*3 ); // start at 4th element
var z1 = new Float64Array( z0.buffer, z0.BYTES_PER_ELEMENT*2 ); // start at 3rd element
dmap2( 3, x1, -2, y1, 1, z1, 1, add );
// z0 => <Float64Array>[ 0.0, 0.0, -4.0, -1.0, 1.0, 0.0 ]
dmap2.ndarray( N, x, strideX, offsetX, y, strideY, offsetY, z, strideZ, offsetZ, fcn )
Applies a binary function to double-precision floating-point strided input arrays and assigns results to a double-precision floating-point strided output array using alternative indexing semantics.
var Float64Array = require( '@stdlib/array/float64' );
var add = require( '@stdlib/math/base/ops/add' );
var x = new Float64Array( [ -1.0, -2.0, -3.0, -4.0, -5.0 ] );
var y = new Float64Array( [ 1.0, 1.0, 2.0, 2.0, 3.0 ] );
var z = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0 ] );
dmap2.ndarray( x.length, x, 1, 0, y, 1, 0, z, 1, 0, add );
// z => <Float64Array>[ 0.0, -1.0, -1.0, -2.0, -2.0 ]
The function accepts the following additional 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 Float64Array = require( '@stdlib/array/float64' );
var add = require( '@stdlib/math/base/ops/add' );
var x = new Float64Array( [ -1.0, -2.0, -3.0, -4.0, -5.0, -6.0 ] );
var y = new Float64Array( [ 1.0, 1.0, 2.0, 2.0, 3.0, 3.0 ] );
var z = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );
dmap2.ndarray( 3, x, 2, 1, y, -1, y.length-1, z, 1, 3, add );
// z => <Float64Array>[ 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 Float64Array = require( '@stdlib/array/float64' );
var add = require( '@stdlib/math/base/ops/add' );
var dmap2 = require( '@stdlib/strided/base/dmap2' );
var x = filledarrayBy( 10, 'float64', discreteUniform( -100, 100 ) );
console.log( x );
var y = filledarrayBy( x.length, 'float64', discreteUniform( -100, 100 ) );
console.log( y );
var z = new Float64Array( x.length );
console.log( z );
dmap2.ndarray( x.length, x, 1, 0, y, -1, y.length-1, z, 1, 0, add );
console.log( z );
C APIs
Usage
#include "stdlib/strided/base/dmap2.h"
stdlib_strided_dmap2( N, *X, strideX, *Y, strideY, *Z, strideZ, fcn )
Applies a binary function to double-precision floating-point strided input arrays and assigns results to a double-precision floating-point strided output array.
#include <stdint.h>
static double add( const double x, const double y ) {
return x + y;
}
double X[] = { 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 };
double Y[] = { 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 };
double Z[] = { 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 };
int64_t N = 6;
stdlib_strided_dmap2( N, X, 1, Y, 1, Z, 1, add );
The function accepts the following arguments:
- N:
[in] int64_tnumber of indexed elements. - X:
[in] double*input array. - strideX
[in] int64_tindex increment forX. - Y:
[in] double*input array. - strideY:
[in] int64_tindex increment forY. - Z:
[out] double*output array. - strideZ:
[in] int64_tindex increment forZ. - fcn:
[in] double (*fcn)( double, double )binary function to apply.
void stdlib_strided_dmap2( const int64_t N, const double *X, const int64_t strideX, const double *Y, const int64_t strideY, double *Z, const int64_t strideZ, double (*fcn)( double, double ) );
Examples
#include "stdlib/strided/base/dmap2.h"
#include <stdint.h>
#include <stdio.h>
#include <inttypes.h>
// Define a callback:
static double add( const double x, const double y ) {
return x + y;
}
int main() {
// Create input strided arrays:
double X[] = { 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 };
double Y[] = { 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 };
// Create an output strided array:
double Z[] = { 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;
int64_t strideZ = 1;
// Apply the callback:
stdlib_strided_dmap2( N, X, strideX, Y, strideY, Z, strideZ, add );
// Print the results:
for ( int64_t i = 0; i < N; i++ ) {
printf( "Z[ %"PRId64" ] = %lf\n", i, Z[ i ] );
}
}