@stdlib/math-strided-special-dmskrsqrt
v0.2.2
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Compute the reciprocal square root for each element in a double-precision floating-point strided array according to a strided mask array.
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dmskrsqrt
Compute the reciprocal square root for each element in a double-precision floating-point strided array according to a strided mask array.
Installation
npm install @stdlib/math-strided-special-dmskrsqrt
Usage
var dmskrsqrt = require( '@stdlib/math-strided-special-dmskrsqrt' );
dmskrsqrt( N, x, sx, m, sm, y, sy )
Computes the reciprocal square root for each element in a double-precision floating-point strided array x
according to a strided mask array and assigns the results to elements in a double-precision floating-point strided array y
.
var Float64Array = require( '@stdlib/array-float64' );
var Uint8Array = require( '@stdlib/array-uint8' );
var x = new Float64Array( [ 0.0, 4.0, 9.0, 12.0, 24.0 ] );
var m = new Uint8Array( [ 0, 0, 1, 0, 1 ] );
var y = new Float64Array( x.length );
dmskrsqrt( x.length, x, 1, m, 1, y, 1 );
// y => <Float64Array>[ Infinity, 0.5, 0.0, ~0.289, 0.0 ]
The function accepts the following arguments:
- N: number of indexed elements.
- x: input
Float64Array
. - sx: index increment for
x
. - m: mask
Uint8Array
. - sm: index increment for
m
. - y: output
Float64Array
. - sy: index increment for
y
.
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 Uint8Array = require( '@stdlib/array-uint8' );
var x = new Float64Array( [ 0.0, 4.0, 9.0, 12.0, 24.0, 64.0 ] );
var m = new Uint8Array( [ 0, 0, 1, 0, 1, 1 ] );
var y = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );
dmskrsqrt( 3, x, 2, m, 2, y, -1 );
// y => <Float64Array>[ 0.0, 0.0, Infinity, 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 Uint8Array = require( '@stdlib/array-uint8' );
// Initial arrays...
var x0 = new Float64Array( [ 0.0, 4.0, 9.0, 12.0, 24.0, 64.0 ] );
var m0 = new Uint8Array( [ 0, 0, 1, 0, 1, 1 ] );
var y0 = 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 m1 = new Uint8Array( m0.buffer, m0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
var y1 = new Float64Array( y0.buffer, y0.BYTES_PER_ELEMENT*3 ); // start at 4th element
dmskrsqrt( 3, x1, -2, m1, -2, y1, 1 );
// y0 => <Float64Array>[ 0.0, 0.0, 0.0, 0.0, ~0.289, 0.5 ]
dmskrsqrt.ndarray( N, x, sx, ox, m, sm, om, y, sy, oy )
Computes the reciprocal square root for each element in a double-precision floating-point strided array x
according to a strided mask array and assigns the results to elements in a double-precision floating-point strided array y
using alternative indexing semantics.
var Float64Array = require( '@stdlib/array-float64' );
var Uint8Array = require( '@stdlib/array-uint8' );
var x = new Float64Array( [ 0.0, 4.0, 9.0, 12.0, 24.0 ] );
var m = new Uint8Array( [ 0, 0, 1, 0, 1 ] );
var y = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0 ] );
dmskrsqrt.ndarray( x.length, x, 1, 0, m, 1, 0, y, 1, 0 );
// y => <Float64Array>[ Infinity, 0.5, 0.0, ~0.289, 0.0 ]
The function accepts the following additional arguments:
- ox: starting index for
x
. - om: starting index for
m
. - oy: 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
,
var Float64Array = require( '@stdlib/array-float64' );
var Uint8Array = require( '@stdlib/array-uint8' );
var x = new Float64Array( [ 0.0, 4.0, 9.0, 12.0, 24.0, 64.0 ] );
var m = new Uint8Array( [ 0, 0, 1, 0, 1, 1 ] );
var y = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );
dmskrsqrt.ndarray( 3, x, 2, 1, m, 2, 1, y, -1, y.length-1 );
// y => <Float64Array>[ 0.0, 0.0, 0.0, 0.0, ~0.289, 0.5 ]
Examples
var uniform = require( '@stdlib/random-base-uniform' );
var Float64Array = require( '@stdlib/array-float64' );
var Uint8Array = require( '@stdlib/array-uint8' );
var dmskrsqrt = require( '@stdlib/math-strided-special-dmskrsqrt' );
var x = new Float64Array( 10 );
var m = new Uint8Array( 10 );
var y = new Float64Array( 10 );
var i;
for ( i = 0; i < x.length; i++ ) {
x[ i ] = uniform( 0.0, 200.0 );
if ( uniform( 0.0, 1.0 ) < 0.5 ) {
m[ i ] = 1;
}
}
console.log( x );
console.log( m );
console.log( y );
dmskrsqrt.ndarray( x.length, x, 1, 0, m, 1, 0, y, -1, y.length-1 );
console.log( y );
C APIs
Usage
#include "stdlib/math/strided/special/dmskrsqrt.h"
stdlib_strided_dmskrsqrt( N, *X, strideX, *Mask, strideMask, *Y, strideY )
Computes the reciprocal square root for each element in a double-precision floating-point strided array X
according to a strided mask array and assigns the results to elements in a double-precision floating-point strided array Y
.
#include <stdint.h>
const double X[] = { 0.0, 4.0, 9.0, 12.0, 24.0, 64.0, 81.0, 101.0 };
const uint8_t Mask[] = { 0, 0, 1, 0, 1, 1, 0, 0 };
double Y[] = { 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 };
const int64_t N = 4;
stdlib_strided_dmskrsqrt( N, X, 2, Mask, 2, Y, 2 );
The function accepts the following arguments:
- N:
[in] int64_t
number of indexed elements. - X:
[in] double*
input array. - strideX:
[in] int64_t
index increment forX
. - Mask:
[in] uint8_t*
mask array. - strideMask:
[in] int64_t
index increment forMask
. - Y:
[out] double*
output array. - strideY:
[in] int64_t
index increment forY
.
void stdlib_strided_dmskrsqrt( const int64_t N, const double *X, const int64_t strideX, const uint8_t *Mask, const int64_t strideMask, double *Y, const int64_t strideY );
Examples
#include "stdlib/math/strided/special/dmskrsqrt.h"
#include <stdint.h>
#include <stdio.h>
int main( void ) {
// Create an input strided array:
const double X[] = { 0.0, 4.0, 9.0, 12.0, 24.0, 64.0, 81.0, 101.0 };
// Create a mask strided array:
const uint8_t M[] = { 0, 0, 1, 0, 1, 1, 0, 0 };
// Create an output strided array:
double Y[] = { 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 };
// Specify the number of elements:
const int64_t N = 4;
// Specify the stride lengths:
const int64_t strideX = 2;
const int64_t strideM = 2;
const int64_t strideY = 2;
// Compute the results:
stdlib_strided_dmskrsqrt( N, X, strideX, M, strideM, Y, strideY );
// Print the results:
for ( int i = 0; i < 8; i++ ) {
printf( "Y[ %i ] = %lf\n", i, Y[ i ] );
}
}
See Also
@stdlib/math-strided/special/dmsksqrt
: compute the principal square root for each element in a double-precision floating-point strided array according to a strided mask array.@stdlib/math-strided/special/dsqrt
: compute the principal square root for each element in a double-precision floating-point strided array.@stdlib/math-strided/special/smskrsqrt
: compute the reciprocal square root for each element in a single-precision floating-point strided array according to a strided mask 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.
Community
License
See LICENSE.
Copyright
Copyright © 2016-2024. The Stdlib Authors.