def COP_path(signal):
	""" Returns total length of the COP path
	Input: 
	signal  --  2-dim array with shape (channel, samples) 
				(on the index 0 - samples from channel x, on index 1 - samples from channel y) 
	Output: 
	cop   	--  float
	cop_x  	--  float
	cop_y  	--  float
	"""

	cop = sum([calculate_distance(signal[:,index], signal[:, index+1]) for index in xrange(signal.shape[1]-1)])
	cop_x = sum([calculate_distance(signal[0,index], signal[0, index+1]) for index in xrange(signal.shape[1]-1)])
	cop_y = sum([calculate_distance(signal[1,index], signal[1, index+1]) for index in xrange(signal.shape[1]-1)])
	return cop, cop_x, cop_y