def METHOD_NAME(aM=0.5,aN=0.5):
	"""
	Produces a compact array with weights for bilinear interpolation, where
	aN,aM in [0,1] are distances in the chordwise and spanwise directions 
	such that:
		- (aM,aN)=(0,0) --> quantity at vertex 0
		- (aM,aN)=(1,0) --> quantity at vertex 1
		- (aM,aN)=(1,1) --> quantity at vertex 2
		- (aM,aN)=(0,1) --> quantity at vertex 3
	"""
	wcv=np.array([ (1-aM)*(1-aN), aM*(1-aN), aM*aN, aN*(1-aM) ])
	return wcv 