srsqrt
Compute the reciprocal square root for each element in a single-precision floating-point strided array.
Usage
var srsqrt = require( '@stdlib/math/strided/special/srsqrt' );
srsqrt( N, x, strideX, y, strideY )
Computes the reciprocal square root for each element in a single-precision floating-point strided array x and assigns the results to elements in a single-precision floating-point strided array y.
var Float32Array = require( '@stdlib/array/float32' );
var x = new Float32Array( [ 1.0, 4.0, 9.0, 12.0, 24.0 ] );
// Perform operation in-place:
srsqrt( x.length, x, 1, x, 1 );
// x => <Float32Array>[ 1.0, 0.5, ~0.333, ~0.289, ~0.204 ]
The function accepts the following arguments:
- N: number of indexed elements.
- x: input
Float32Array. - strideX: index increment for
x. - y: output
Float32Array. - strideY: index increment for
y.
The N and stride parameters determine which elements in x and y 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 x = new Float32Array( [ 1.0, 4.0, 9.0, 12.0, 24.0, 64.0 ] );
var y = new Float32Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );
srsqrt( 3, x, 2, y, -1 );
// y => <Float32Array>[ ~0.204, ~0.333, 1.0, 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' );
// Initial arrays...
var x0 = new Float32Array( [ 1.0, 4.0, 9.0, 12.0, 24.0, 64.0 ] );
var y0 = 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
srsqrt( 3, x1, -2, y1, 1 );
// y0 => <Float32Array>[ 0.0, 0.0, 0.0, 0.125, ~0.289, 0.5 ]
srsqrt.ndarray( N, x, strideX, offsetX, y, strideY, offsetY )
Computes the reciprocal square root for each element in a single-precision floating-point strided array x and assigns the results to elements in a single-precision floating-point strided array y using alternative indexing semantics.
var Float32Array = require( '@stdlib/array/float32' );
var x = new Float32Array( [ 1.0, 4.0, 9.0, 12.0, 24.0 ] );
var y = new Float32Array( [ 0.0, 0.0, 0.0, 0.0, 0.0 ] );
srsqrt.ndarray( x.length, x, 1, 0, y, 1, 0 );
// y => <Float32Array>[ 1.0, 0.5, ~0.333, ~0.289, ~0.204 ]
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 offsetX and offsetY 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 Float32Array = require( '@stdlib/array/float32' );
var x = new Float32Array( [ 1.0, 4.0, 9.0, 12.0, 24.0, 64.0 ] );
var y = new Float32Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );
srsqrt.ndarray( 3, x, 2, 1, y, -1, y.length-1 );
// y => <Float32Array>[ 0.0, 0.0, 0.0, 0.125, ~0.289, 0.5 ]
Examples
var uniform = require( '@stdlib/random/base/uniform' );
var Float32Array = require( '@stdlib/array/float32' );
var srsqrt = require( '@stdlib/math/strided/special/srsqrt' );
var x = new Float32Array( 10 );
var y = new Float32Array( 10 );
var i;
for ( i = 0; i < x.length; i++ ) {
x[ i ] = uniform( 0.0, 200.0 );
}
console.log( x );
console.log( y );
srsqrt.ndarray( x.length, x, 1, 0, y, -1, y.length-1 );
console.log( y );
C APIs
Usage
#include "stdlib/math/strided/special/srsqrt.h"
stdlib_strided_srsqrt( N, *X, strideX, *Y, strideY )
Computes the reciprocal square root for each element in a single-precision floating-point strided array X and assigns the results to elements in a single-precision floating-point strided array Y.
#include <stdint.h>
const float X[] = { 1.0, 4.0, 9.0, 12.0, 24.0, 64.0, 81.0, 101.0 };
float Y[] = { 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 };
const int64_t N = 4;
stdlib_strided_srsqrt( N, X, 2, Y, 2 );
The function accepts the following arguments:
- N:
[in] int64_tnumber of indexed elements. - X:
[in] float*input array. - strideX:
[in] int64_tindex increment forX. - Y:
[out] float*output array. - strideY:
[in] int64_tindex increment forY.
void stdlib_strided_srsqrt( const int64_t N, const float *X, const int64_t strideX, float *Y, const int64_t strideY );
Examples
#include "stdlib/math/strided/special/srsqrt.h"
#include <stdint.h>
#include <stdio.h>
int main( void ) {
// Create an input strided array:
const float X[] = { 1.0, 4.0, 9.0, 12.0, 24.0, 64.0, 81.0, 101.0 };
// Create an output strided array:
float 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 strideY = 2;
// Compute the results:
stdlib_strided_srsqrt( N, X, strideX, Y, strideY );
// Print the results:
for ( int i = 0; i < 8; i++ ) {
printf( "Y[ %i ] = %f\n", i, Y[ i ] );
}
}