Plotting 2-D regions without prior knowing the numeric limits
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Hello,
I'm trying to plot a closed 2-D region defined by a set of linear inequalities (it could be a triangle, rectangle, etc., you know). Those inequalities are defined using symbolic variables and their coeficients are results from previous calculations. I tried using solve function (with 'returnconditions' to true) but I can't extract the validity intervals of the variables from the result.
I saw other answers around this topic that defined a meshgrid and checked if the conditions hold at each point of the grid. The problem is that I don't have the knowledge of the limits of the region I'm trying to plot, so I can't define a grid.
As an example, from one of the runs, i get a "1x4 sym":
[ 13/10 < K1 + 2*K2, -1/5 < 2*K2 - K1, 1/10 - (23*5^(1/2))/50 < - K1 - K2/2 - (5^(1/2)*K2)/5, - (23*5^(1/2))/50 - 1/10 < K1 + K2/2 - (5^(1/2)*K2)/5]
where K1 and K2 are the variables.
I would like to obtain the lowest and highest K1 and K2 that allow the conditions to be true, so I can make the meshgrid and plot the result. If that's not posible, obtaining a set of points satisfying the inequality system could be useful (as long as the points are distributed along the region).
Thanks for your help.
Accepted Answer
Torsten
on 15 Jul 2022
0 votes
3 Comments
Marcos Moreno
on 15 Jul 2022
Could you explain how can I obtain the matrix A and b from the sym variable that I have so I can use plotregion?
Maybe
can help, but once you get A and b treating your inequalities as equalities, i think you will have to change the signs of the i-th row of A and the element b(i) manually if the resulting inequality would be >= instead of <=.
Do you understand what I mean ?
Here is another plotting tool once you have A and b correctly:
Marcos Moreno
on 15 Jul 2022
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