I need to 3d plot the code but there is an error can I get help with fixing the error

F = [-40:20:40];

x = 0.1:0.8;

y = 0.1:0.4;

sigma_p = @(x,y) F/(.8*x*y); 

sigma_mx = @(x,y) (F*y)/(1/12*(x)*(y)^3);

sigma_my = @(x,y) (F*x)/(1/12*(y)*(x)^3);

sigma_net = @(x,y) sigma_p  +sigma_mx + sigma_my

figure

plot3(x,y,sigma_net)

Answer 1

[Walter Roberson]

sigma_net = @(x,y) sigma_p(x,y)  + sigma_mx(x,y) + sigma_my(x,y);

plot3(x, y, sigma_net(x,y))