source 2007 Bernstein--Lange assume Z2 = 1 compute R1 = X1 compute R2 = Y1 compute R3 = Z1 compute R4 = X2 compute R5 = Y2 compute R7 = R1+R2 compute R6 = R4+R5 compute R1 = R1 R4 compute R2 = R2 R5 compute R7 = R7 R6 compute R7 = R7-R1 compute R7 = R7-R2 compute R7 = R7 R3 compute R6 = R1 R2 compute R6 = d R6 compute R2 = R2-R1 compute R2 = R2 R3 compute R3 = R3^2 compute R1 = R3-R6 compute R3 = R3+R6 compute R2 = R2 R3 compute R3 = R3 R1 compute R1 = R1 R7 compute R3 = c R3 compute X3 = R1 compute Y3 = R2 compute Z3 = R3