Plot with matrices - surfaces

I have the informations and I did the graphic using the commands:

t = 4;
a1 = [1 2 8 9 12]; a2 = [1 2 8 9 12];
b1 = [-2 0 2 7 8]; b2 = [-5 -1 0 -2 5];
c1 = [1 2 3 5 2]; c2 = [1 1 -1 4 0];

figure (1)
k = 1: 1 t + 1;
Plot3 (k-1, a1, k-k + 1 'k * -, k-1, a2, k, k + 1' k * -, k-1, b 1, k, k + 0.5, 'b * -, k-1, b2, k, k + 0,5,' b * -, k-1, c1, k 0 + k 'r * -, k-1, c 2, k 0 + k 'r * -')
xlabel ('k')
ylabel ('x_1')
zlabel ( '\ alpha')
legend ('(\ alpha = 1)', '(\ alpha = 1)', '(\ alpha = 0.5)', '(\ alpha = 0.5)', '(\ alpha = 0)' '(\ alpha = 0)')

I wanted a surface and not a graphic 3D. The surface would be built connecting the points which would give a "triangle" over the period k.

I tried to use the comands "mesh" or "surf" or "stem3" of matlab but did not work.

Thanks.

[Massimo Zanetti]

Fix line with plot3 and reupload the code.