function dmeanpw( N, x, strideX, offsetX ) {
	if ( N <= 0 ) {
		return NaN;
	}
	if ( N === 1 || strideX === 0 ) {
		return x[ offsetX ];
	}
	return dsumpw( N, x, strideX, offsetX ) / N;
}
Computes the arithmetic mean of a double-precision floating-point strided array using pairwise summation.

@param {PositiveInteger} N - number of indexed elements
@param {Float64Array} x - input array
@param {integer} strideX - stride length
@param {NonNegativeInteger} offsetX - starting index
@returns {number} arithmetic mean

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

var x = new Float64Array( [ 2.0, 1.0, 2.0, -2.0, -2.0, 2.0, 3.0, 4.0 ] );

var v = dmeanpw( 4, x, 2, 1 );
// returns 1.25