def fwd(coeffs, x, y):
	""" Transforms projected coordinates from the Old Greek datum to GGRS87.
	Params:
		coeffs (float sequence): the 12 coefficients of the current Hatt map block [A0...B0...]
		x, y (floats): Easting, Northing Hatt coordinates of a point
	Returns:
		(float tuple): Easting, Northing GGRS87 coordinates
	"""
	#
	# | E |   | A0 |   | A1 + A3*x ' A2 + A4*y + A5*x | | x |
	# |   | = |    | + |---------- ' ---------------- | |   |
	# | N |   | B0 |   | B1 + B3*x ' B2 + B4*y + B5*x | | y |
	#
	if len(coeffs) != 12: 
		raise ValueError("Wrong number of hatt coefficients.")
	
	x2 = pow(x,2)
	y2 = pow(y,2)
	xy = x * y
	e = coeffs[0] + coeffs[1]*x + coeffs[2]*y + coeffs[3]*x2 + coeffs[4]*y2 + coeffs[5]*xy
	n = coeffs[6] + coeffs[7]*x + coeffs[8]*y + coeffs[9]*x2 + coeffs[10]*y2 + coeffs[11]*xy
	return (e, n)