a=130;
b=0.5;
c=4000;
d=25;
[X1,X2]=meshgrid(0.0001:0.001:0.035,0.0001:0.001:0.025);
L=a-b./X1-c*X2-d*X1./X2;
[X1,X2]=meshgrid(0.005:0.0001:0.022,0.005:0.0001:0.014);
L=a-b./X1-c*X2-d*X1./X2;
mesh(X1,X2,L)
xlabel('X1');...
ylabel('X2');...
