# sqrt > Compute the principal [square root][square-root] of each element in a strided array.
The principal [square root][square-root] is defined as
Principal square root
## Usage ```javascript var sqrt = require( '@stdlib/math/strided/special/sqrt' ); ``` #### sqrt( N, x, strideX, y, strideY ) Computes the principal [square root][square-root] of each element in a strided array `x` and assigns the results to elements in a strided array `y`. ```javascript var Float64Array = require( '@stdlib/array/float64' ); var x = new Float64Array( [ 0.0, 4.0, 9.0, 12.0, 24.0 ] ); // Perform operation in-place: sqrt( x.length, x, 1, x, 1 ); // x => [ 0.0, 2.0, 3.0, ~3.464, ~4.899 ] ``` The function accepts the following arguments: - **N**: number of indexed elements. - **x**: input array-like object. - **strideX**: index increment for `x`. - **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, ```javascript var Float64Array = require( '@stdlib/array/float64' ); 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 ] ); sqrt( 3, x, 2, y, -1 ); // y => [ ~4.899, 3.0, 0.0, 0.0, 0.0, 0.0 ] ``` Note that indexing is relative to the first index. To introduce an offset, use [`typed array`][mdn-typed-array] views. ```javascript var Float64Array = require( '@stdlib/array/float64' ); // 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 sqrt( 3, x1, -2, y1, 1 ); // y0 => [ 0.0, 0.0, 0.0, 8.0, ~3.464, 2.0 ] ``` #### sqrt.ndarray( N, x, strideX, offsetX, y, strideY, offsetY ) Computes the principal [square root][square-root] of each element in a strided array `x` and assigns the results to elements in a strided array `y` using alternative indexing semantics. ```javascript var Float64Array = require( '@stdlib/array/float64' ); 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 ] ); sqrt.ndarray( x.length, x, 1, 0, y, 1, 0 ); // y => [ 0.0, 2.0, 3.0, ~3.464, ~4.899 ] ``` The function accepts the following additional arguments: - **offsetX**: starting index for `x`. - **offsetY**: starting index for `y`. While [`typed array`][mdn-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`, ```javascript var Float64Array = require( '@stdlib/array/float64' ); 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 ] ); sqrt.ndarray( 3, x, 2, 1, y, -1, y.length-1 ); // y => [ 0.0, 0.0, 0.0, 8.0, ~3.464, 2.0 ] ```
## Examples ```javascript var uniform = require( '@stdlib/random/base/uniform' ).factory; var filledarray = require( '@stdlib/array/filled' ); var dtypes = require( '@stdlib/array/dtypes' ); var gfillBy = require( '@stdlib/blas/ext/base/gfill-by' ); var sqrt = require( '@stdlib/math/strided/special/sqrt' ); var dt; var x; var y; var i; dt = dtypes(); for ( i = 0; i < dt.length; i++ ) { x = filledarray( 0.0, 10, dt[ i ] ); gfillBy( x.length, x, 1, uniform( 0.0, 100.0 ) ); console.log( x ); y = filledarray( 0.0, x.length, 'generic' ); console.log( y ); sqrt.ndarray( x.length, x, 1, 0, y, -1, y.length-1 ); console.log( y ); console.log( '' ); } ```