[general]
name = Catalan;
comments = Catalan surface. Eugene Charles Catalan (1814-1894).;
a1_min = -360;
a1_max = 360;
a1_steps = 100;
a2_min = -2; 
a2_max = 2;
a2_steps = 40;

[formula]
S2 = rad(sinh(A2 / 2));
C2 = rad(cosh(A2));

X = rad(A1) - sin(A1) * C2; 
Y = 4 * sin(0.5 * A1) * S2;
Z = 1 - cos(A1) * C2;