function unary0d( x, y, fcn, clbk, thisArg ) {
	var ox = x.offset;
	var oy = y.offset;
	var v = clbk.call( thisArg, x.accessors[ 0 ]( x.data, ox ), 0, [ ox, oy ], [ x, y ] ); // eslint-disable-line max-len
	if ( v !== void 0 ) {
		y.accessors[ 1 ]( y.data, oy, fcn( v ) );
	}
}
Applies a unary function to each element retrieved from a zero-dimensional input ndarray according to a callback function and assigns results to elements in an equivalently shaped output ndarray.

@private
@param {Object} x - object containing input ndarray meta data
@param {string} x.dtype - data type
@param {Collection} x.data - data buffer
@param {NonNegativeIntegerArray} x.shape - dimensions
@param {IntegerArray} x.strides - stride lengths
@param {NonNegativeInteger} x.offset - index offset
@param {string} x.order - specifies whether `x` is row-major (C-style) or column-major (Fortran-style)
@param {Array<Function>} x.accessors - data buffer accessors
@param {Object} y - object containing output ndarray meta data
@param {string} y.dtype - data type
@param {Collection} y.data - data buffer
@param {NonNegativeIntegerArray} y.shape - dimensions
@param {IntegerArray} y.strides - stride lengths
@param {NonNegativeInteger} y.offset - index offset
@param {string} y.order - specifies whether `y` is row-major (C-style) or column-major (Fortran-style)
@param {Array<Function>} y.accessors - data buffer accessors
@param {Function} fcn - unary function to apply to callback return values
@param {Callback} clbk - callback
@param {*} [thisArg] - callback execution context
@returns {void}

@example
var cidentityf = require( '@stdlib/complex/float32/base/identity' );
var Complex64Array = require( '@stdlib/array/complex64' );
var Complex64 = require( '@stdlib/complex/float32/ctor' );
var realf = require( '@stdlib/complex/float32/real' );
var imagf = require( '@stdlib/complex/float32/imag' );

function scale( z ) {
    return new Complex64( realf(z)*10.0, imagf(z)*10.0 );
}

// Create data buffers:
var xbuf = new Complex64Array( [ 1.0, 2.0, 3.0, 4.0 ] );
var ybuf = new Complex64Array( 2 );

// Define the shape of the input and output arrays:
var shape = [];

// Define the array strides:
var sx = [ 0 ];
var sy = [ 0 ];

// Define the index offsets:
var ox = 1;
var oy = 0;

// Define getters and setters:
function getter( buf, idx ) {
    return buf.get( idx );
}

function setter( buf, idx, value ) {
    buf.set( value, idx );
}

// Create the input and output ndarray-like objects:
var x = {
    'dtype': 'complex64',
    'data': xbuf,
    'shape': shape,
    'strides': sx,
    'offset': ox,
    'order': 'row-major',
    'accessors': [ getter, setter ]
};
var y = {
    'dtype': 'complex64',
    'data': ybuf,
    'shape': shape,
    'strides': sy,
    'offset': oy,
    'order': 'row-major',
    'accessors': [ getter, setter ]
};

// Apply the unary function:
unary0d( x, y, scale, cidentityf );

var v = y.data.get( 0 );

var re = realf( v );
// returns 30.0

var im = imagf( v );
// returns 40.0