ψ1 + ½ Rx2 = 1⁄8 Rc2 (ch 2α1 + 1),

(14)

ψ2 + ½ Ry2 = 1⁄8 Rc2 (ch 2α1 − 1),

(15)

constant values.

In a similar way the more general state of motion may be analysed, given by

w = m ch 2 (ζ − γ), γ = α + βi,

(16)

as giving a homogeneous strain velocity to the confocal system; to which may be added a circulation, represented by an additional term mζ in w.

Similarly, with