Generalized elastic curves are solutions of the differential equation
K'' = b + (a - 1/2 * K*K)*K
where K is the curvature of the curve. The curve itself is then the
solution of
c'' = K*Jc'
where J denotes the anti-clockwise rotation by 90°. Change the initial
values K, K', initial point, initial direction and/or parameters a or b to get
another elastic curve. Parameter 'Stepsize K' is used for the integration of
equation K''=..., parameter 'Stepsize' is used for equation c''=... .
