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Compute the reciprocal square root for each element in a strided array.
The reciprocal of the principal square root is defined as
import rsqrt from 'https://cdn.jsdelivr.net/gh/stdlib-js/math-strided-special-rsqrt@esm/index.mjs';Computes the reciprocal square root for each element in a strided array x and assigns the results to elements in a strided array y.
import Float64Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-float64@esm/index.mjs';
var x = new Float64Array( [ 0.0, 4.0, 9.0, 12.0, 24.0 ] );
// Perform operation in-place:
rsqrt( x.length, 'float64', x, 1, 'float64', x, 1 );
// x => <Float64Array>[ Infinity, 0.5, ~0.333, ~0.289, ~0.204 ]The function accepts the following arguments:
- N: number of indexed elements.
- dtypeX: data type for
x. - x: input array-like object.
- strideX: index increment for
x. - dtypeY: data type for
y. - y: output array-like object.
- 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 the first N elements of y in reverse order,
import Float64Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-float64@esm/index.mjs';
var x = new Float64Array( [ 0.0, 4.0, 9.0, 12.0, 24.0, 64.0 ] );
var y = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );
rsqrt( 3, 'float64', x, 2, 'float64', y, -1 );
// y => <Float64Array>[ ~0.204, ~0.333, Infinity, 0.0, 0.0, 0.0 ]Note that indexing is relative to the first index. To introduce an offset, use typed array views.
import Float64Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-float64@esm/index.mjs';
// Initial arrays...
var x0 = new Float64Array( [ 0.0, 4.0, 9.0, 12.0, 24.0, 64.0 ] );
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 y1 = new Float64Array( y0.buffer, y0.BYTES_PER_ELEMENT*3 ); // start at 4th element
rsqrt( 3, 'float64', x1, -2, 'float64', y1, 1 );
// y0 => <Float64Array>[ 0.0, 0.0, 0.0, 0.125, ~0.289, 0.5 ]Computes the reciprocal square root for each element in a strided array x and assigns the results to elements in a strided array y using alternative indexing semantics.
import Float64Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-float64@esm/index.mjs';
var x = new Float64Array( [ 0.0, 4.0, 9.0, 12.0, 24.0 ] );
var y = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0 ] );
rsqrt.ndarray( x.length, 'float64', x, 1, 0, 'float64', y, 1, 0 );
// y => <Float64Array>[ Infinity, 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,
import Float64Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-float64@esm/index.mjs';
var x = new Float64Array( [ 0.0, 4.0, 9.0, 12.0, 24.0, 64.0 ] );
var y = new Float64Array( [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ] );
rsqrt.ndarray( 3, 'float64', x, 2, 1, 'float64', y, -1, y.length-1 );
// y => <Float64Array>[ 0.0, 0.0, 0.0, 0.125, ~0.289, 0.5 ]<!DOCTYPE html>
<html lang="en">
<body>
<script type="module">
var uniform = require( 'https://cdn.jsdelivr.net/gh/stdlib-js/random-base-uniform' ).factory;
import filledarray from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-filled@esm/index.mjs';
import filledarrayBy from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-filled-by@esm/index.mjs';
import dtypes from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-typed-real-float-dtypes@esm/index.mjs';
import rsqrt from 'https://cdn.jsdelivr.net/gh/stdlib-js/math-strided-special-rsqrt@esm/index.mjs';
var dt;
var x;
var y;
var i;
dt = dtypes();
for ( i = 0; i < dt.length; i++ ) {
x = filledarrayBy( 10, dt[ i ], uniform( 0.0, 100.0 ) );
console.log( x );
y = filledarray( 0.0, x.length, 'generic' );
console.log( y );
rsqrt.ndarray( x.length, dt[ i ], x, 1, 0, 'generic', y, -1, y.length-1 );
console.log( y );
console.log( '' );
}
</script>
</body>
</html>@stdlib/math-strided/special/drsqrt: compute the reciprocal square root for each element in a double-precision floating-point strided array.@stdlib/math-strided/special/sqrt: compute the principal square root for each element in a strided array.@stdlib/math-strided/special/srsqrt: compute the reciprocal square root for each element in a single-precision floating-point strided array.
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