[Gmsh] problem with hyperbolic paraboloid

[Giuseppe Zagari]

Hi

I need the gmsh code for create an hyperbolic paraboloid:
 z = x^2-y^2,  with x=[-L, L] and y=[L,L]
I am not sure about the factor k that controls the BSpline.


k=3/4;
L=1/2;
Point(1) = {-L, -L,    0};
Point(2) = { 0, -L, -L*k};
Point(3) = { L, -L,    0};
Point(4) = {-L,  0,  L*k};
Point(6) = { L,  0,  L*k};
Point(7) = {-L,  L,    0};
Point(8) = { 0,  L, -L*k};
Point(9) = { L,  L,    0};
BSpline(1) = {1, 2, 3};
BSpline(3) = {7, 8, 9};
BSpline(4) = {1, 4, 7};
BSpline(6) = {3, 6, 9};
Line Loop(7) = {4, 3, -6, -1};
Ruled Surface(8) = {7};


Also, I would like to get the half symmetric part.
Can someone help me?

Giuseppe