function updateCentroid( ndims, N, C, strideC, offsetC, V, strideV, offsetV ) {
	var delta;
	var ci;
	var i;

	for ( i = 0; i < ndims; i++ ) {
		ci = C[ offsetC ];
		delta = V[ offsetV ] - ci;
		ci += delta / N;
		C[ offsetC ] = ci;

		offsetC += strideC;
		offsetV += strideV;
	}
	return C;
}
Updates a centroid.

## Notes

-   Uses Welford's algorithm for updating an arithmetic mean.

@private
@param {PositiveInteger} ndims - number of dimensions
@param {PositiveInteger} N - number of data points in a cluster
@param {NumericArray} C - strided array containing centroids
@param {PositiveInteger} strideC - centroid column stride
@param {NonNegativeInteger} offsetC - centroid index offset
@param {NumericArray} V - strided array containing a data point
@param {integer} strideV - vector stride
@param {NonNegativeInteger} offsetV - vector index offset
@returns {NumericArray} strided array containing centroids