Abstract
z = snw, dnw and cnw mapping the lines u = const and v = const. onto the z plane respectively:z = snw,−ρ 2 A 2 cos 2ϕ = −2c 2 d 2/k 2 s 2 (&rho 4 + 1/k 2) + &rho 2 (c 4 d 4/k 4 s 4 − k′4/k 4),A = c 2 + s 2 d 2/k 2 s 2−ρ 2 A 2 cos 2ϕ = 2c 2 1 s 2 1 k 2/d 2 1 (ρ 2 + 1/k 2) + ρ2(k′4 c 4 1 s 4 1/d 4 − 1),A = s 2 1 − c 2 1/d 2 1 z = dnw,−ρ 2 A 2 cos 2ϕ = + 2c 2 s 2/d 2 (ρ 4 + k′2) + ρ 2 (c 4 ks 4/d 4 − 1),A = s 2 − c 2/d 2−ρ 2 A 2 cos 2ϕ = −2d 2 1 s 2 1/c 2 1 (ρ 4 + k′2) + ρ 2 (k 4 s 4 1/c 4 1 − d 4 1),A = −c 2 1 + d 2 1 s 2 1/c 2 1 z = cnw,ρ 2 A 2 cos2 2ϕ + 2(AB + E) cos 2ϕ + B 2 − F/ρ 2= [ρ 2 A 2 cos 2ϕ + 2(AB + E)] cos 2ϕ + B 2 − F/ρ 2 = 0B 2 − F/ρ 2 = −2c 2 d 2/k 2 s 2 (ρ 2 − k′2/k 2) + ρ 2 c 4 − d 4 s 4/k 2 s 2,A = −d 2 − c 2 + d 2 c 2/k 2 s 2 = −d 2 s 2 − c 2 + 2c 2 d 2/k 2 s 2,AB + E = c 2 d 2/k 2 s 2 (ρ 2 − k′2/k 2)+ ρ 2 c 4/k 4 s 4 (d 2 s 2 − c 2 + 2k′2 d 2 s 2),B 2 − F/ρ 2 = 2k 2 s 2 1/d 2 1 (ρ 2 − k′2/k 2) + ρ 2 (c 4 1 − d 4 1 s 4 1/d 4 1),A = −(d 2 1 + k′22/k 2 s 2 1/d 2 1), (k 2 s 2 1 = d 2 1 s 2 1 − c 2 1 + d 2 1 c 2 1)AB + E = −k 2 s 2 1/d 2 1 (p 4 − k′2/k 2) − c 2 1 ρ 2 {1 − k′2 s 2 1/d 4 1 (2d 2 1 c 2 1 + d 2 1 s 2 1 − c 2 1)}when u = const = K/2 and V = const = k′/2, they become Cassinians:ρ 2 + 2k′2/k 2 cos 2ϕ ρ 2 + k′4/k 4 = k′4/k 4 + k′2/k 2 = k′2/k 4 = β 4, β = 1/√k′andρ 2 − 2cos 2ϕ ρ 2 + 1 = k′2/k 2 + 1 = 1/k 2 = β 4, β = 1/√k