source 2007 Bernstein--Lange
unified
parameter i
assume i^2 = -1
compute iX2 = i X2
compute C2 = Y2+iX2
compute D2 = Y2-iX2
compute iX1 = i X1
compute C1 = Y1+iX1
compute D1 = Y1-iX1
compute A = Z1 Z2
compute B = 2 A^2
compute C = C1 C2
compute D = D1 D2
compute L = D+C
compute M = Y1 Y2
compute N = 2 M-L
compute E = d M N
compute F = B-E
compute G = B+E
compute X3 = i A F (D-C)
compute Y3 = A G L
compute Z3 = c G F
