# How to plot 3D graphic from sets of inequalities with one discrete axis?

I have 4 sets of inequalities defining a closed region in 2D.

eq = {-2.2935076096752747 - Subscript[K, d] +
6.808229911479505 Subscript[K, i] <
0 && -5.763766885115767 - Subscript[K, d] +
0.009355320091888606 Subscript[K, i] <
0 && -11.502684761149357 - Subscript[K, d] +
0.001987089809253273 Subscript[K, i] < 0 &&
3.46340304560584 - Subscript[K, d] +
0.04542417164482498 Subscript[K, i] > 0 &&
8.537116309367326 - Subscript[K, d] +
0.0037660209728445602 Subscript[K, i] > 0 &&
14.534182608551115 - Subscript[K, d] +
0.001221044796678191 Subscript[K, i] > 0 &&
Kp == 0.5, -1.604921075546996 - Subscript[K, d] +
0.6925589409886266 Subscript[K, i] <
0 && -5.786642271389586 - Subscript[K, d] +
0.009244731146798546 Subscript[K, i] <
0 && -11.509573547679 - Subscript[K, d] +
0.0019844016231937473 Subscript[K, i] < 0 &&
3.3439113785107626 - Subscript[K, d] +
0.05008377356287994 Subscript[K, i] > 0 &&
8.522465980907986 - Subscript[K, d] +
0.003778957659603982 Subscript[K, i] > 0 &&
14.529247935512808 - Subscript[K, d] +
0.0012218569337417472 Subscript[K, i] > 0 &&
Kp == 2.5, -0.8211478234907658 - Subscript[K, d] +
0.3265086224409325 Subscript[K, i] <
0 && -5.802882397109164 - Subscript[K, d] +
0.009138121629927757 Subscript[K, i] <
0 && -11.515757528942748 - Subscript[K, d] +
0.0019817256743999857 Subscript[K, i] < 0 &&
3.124003074539731 - Subscript[K, d] +
0.05675256117367748 Subscript[K, i] > 0 &&
8.50593069778869 - Subscript[K, d] +
0.0037920495232265415 Subscript[K, i] > 0 &&
14.523969834762996 - Subscript[K, d] +
0.0012226709659726972 Subscript[K, i] > 0 && Kp == 5,
0.16873913996616716 - Subscript[K, d] +
0.1853676602926451 Subscript[K, i] <
0 && -5.812793495347904 - Subscript[K, d] +
0.009035141486771207 Subscript[K, i] <
0 && -11.521241128822854 - Subscript[K, d] +
0.0019790617042690774 Subscript[K, i] < 0 &&
2.6930975155249706 - Subscript[K, d] +
0.06857354659267068 Subscript[K, i] > 0 &&
8.487476503798769 - Subscript[K, d] +
0.00380530283044807 Subscript[K, i] > 0 &&
14.518347131293424 - Subscript[K, d] +
0.0012234869204936912 Subscript[K, i] > 0 && Kp == 7.5};


My intention is to find valid PID controller coefficients. First I had the range of Kp from 0.5 to 7.5 and I divided the interval into 4 and find sets of inequalities for corresponding Kp values.

Now I want to plot those 4 planes along the vertical[Kp] axis. But couldn't do it.

I have tried ParametricPlot3D, RegionPlot3d with RegionFunction but none worked. The types of visualizations are not well or seems not work intended.

• What are you looking for? You can change BoxRatios maybe? – Feyre Dec 22 '16 at 9:19
• I am not sure if ı am using this in a right way or not. If right, how to visualize smooth surfaces. Do you know anyway to plot a region with 3rd axis as discrete value – freezer Dec 22 '16 at 11:22
• And ı dont know how to use multiple region functions for different sets of equations. Or do ı need to plot them separately and show all into one as ı did in regionplot? – freezer Dec 22 '16 at 11:24