MATLAB: Plotting a complex inequality

3dcontourMATLAB

Is there any way in Matlab that I can plot this inequality?
q(2p1+p2+p4 -1) <= 2sqrt [ (qp2 + (1-q)/4))*(qp4 + (1-q)/4) ] where q,p1,p2 and p4 are between 0 and 1.
So I have 2 complications here,
  1. How to plot an inequality?
  2. How to plot 4 variables? Can I use color schemes or contour plotting?

Best Answer

For your first question. You can plot an inequality with two variables like this
q = 1;
p4 = 2;
[p1, p2] = meshgrid(linspace(0,1,100));
s = q*(2*p1+p2+p4-1) <= 2*sqrt((q*p2 + (1-q)/4)*(q*p4 + (1-q)/4));
contourf(p1,p2,s+0, 'LineColor', 'flat');
xlabel('p1');
ylabel('p2');
For the second question, I am not sure how you can visualize it. With the help of slice(), it is somewhat possible to visualize 3 variables, but four variables cannot be visualized in a single graphic. Plotting several 2D plots by fixing the values of the other two variables is one of the ways.
Related Question