## Usage ```javascript var toRot90 = require( '@stdlib/ndarray/to-rot90' ); ``` #### toRot90( x\[, options] ) Returns a new [`ndarray`][@stdlib/ndarray/ctor] where an input [`ndarray`][@stdlib/ndarray/ctor] is rotated `90` degrees in a specified plane. ```javascript var array = require( '@stdlib/ndarray/array' ); var x = array( [ [ 1.0, 2.0 ], [ 3.0, 4.0 ] ] ); // returns [ [ 1.0, 2.0 ], [ 3.0, 4.0 ] ] var y = toRot90( x ); // returns [ [ 2.0, 4.0 ], [ 1.0, 3.0 ] ] ``` The function accepts the following arguments: - **x**: input [`ndarray`][@stdlib/ndarray/ctor]. - **options**: function options. The function accepts the following options: - **k**: number of times to rotate by `90` degrees. Positive values rotate counterclockwise. Negative values rotate clockwise. Default: `1`. - **dims**: dimension indices defining the plane of rotation. Must contain exactly two unique dimension indices. If a dimension index is provided as an integer less than zero, the dimension index is resolved relative to the last dimension, with the last dimension corresponding to the value `-1`. Default: `[-2, -1]`.

## Notes - If `options.k > 0`, the function rotates the plane from the first specified dimension toward the second specified dimension. This means that, for a two-dimensional ndarray and `options.dims = [0, 1]`, the function rotates the plane counterclockwise. - If `options.k < 0`, the function rotates the plane from the second specified dimension toward the first specified dimension. This means that, for a two-dimensional ndarray and `options.dims = [0, 1]`, the function rotates the plane clockwise. - Each provided dimension index must reside on the interval `[-ndims, ndims-1]`.

## Examples ```javascript var uniform = require( '@stdlib/random/uniform' ); var ndarray2array = require( '@stdlib/ndarray/to-array' ); var toRot90 = require( '@stdlib/ndarray/to-rot90' ); var x = uniform( [ 3, 3, 3 ], -10.0, 10.0 ); console.log( ndarray2array( x ) ); var y = toRot90( x ); console.log( ndarray2array( y ) ); ```