function dmskmap( N, x, strideX, offsetX, mask, strideMask, offsetMask, y, strideY, offsetY, fcn ) { // eslint-disable-line max-len, max-params
	var ix;
	var im;
	var iy;
	var i;
	if ( N <= 0 ) {
		return y;
	}
	ix = offsetX;
	im = offsetMask;
	iy = offsetY;
	for ( i = 0; i < N; i++ ) {
		if ( mask[ im ] === 0 ) {
			y[ iy ] = fcn( x[ ix ] );
		}
		ix += strideX;
		im += strideMask;
		iy += strideY;
	}
	return y;
}
Applies a unary function to a double-precision floating-point strided input array according to a strided mask array and assigns results to a double-precision floating-point strided output array.

@param {NonNegativeInteger} N - number of indexed elements
@param {Float64Array} x - input array
@param {integer} strideX - `x` stride length
@param {NonNegativeInteger} offsetX - starting `x` index
@param {Uint8Array} mask - mask array
@param {integer} strideMask - `mask` stride length
@param {NonNegativeInteger} offsetMask - starting `mask` index
@param {Float64Array} y - destination array
@param {integer} strideY - `y` stride length
@param {NonNegativeInteger} offsetY - starting `y` index
@param {Function} fcn - unary function to apply
@returns {Float64Array} `y`

@example
var Float64Array = require( '@stdlib/array/float64' );
var Uint8Array = require( '@stdlib/array/uint8' );

function scale( x ) {
    return x * 10.0;
}

var x = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0 ] );
var m = new Uint8Array( [ 0, 0, 1, 0, 0 ] );
var y = new Float64Array( x.length );

dmskmap( x.length, x, 1, 0, m, 1, 0, y, 1, 0, scale );

console.log( y );
// => <Float64Array>[ 10.0, 20.0, 0.0, 40.0, 50.0 ]