name inverted coordinates
variable X
variable Y
variable Z
neutral X = 0
neutral Y = 1
neutral Z = c
satisfying x = Z/X
satisfying y = Z/Y
toaffine x = Z/X
toaffine y = Z/Y
tosystem X = 1/x
tosystem Y = 1/y
tosystem Z = 1
homogweight X = 1
homogweight Y = 1
homogweight Z = 1
