Get the analytical solution of inequalities in Matlab.
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Hello,
x + 2 y + 3 c + 4 d == 3/2 && x + y + c + d == 2 && x >= 2 &&
y < 2 && c < 3 && d > 5
How to solve this inequations to get the solution of x, y, c, and d in Matlab?
Best regards.
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Answers (2)
Walter Roberson
on 3 Sep 2023
Most of the time, MATLAB is not able to solve systems of inequalities.
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Bruno Luong
on 3 Sep 2023
Edited: Bruno Luong
on 3 Sep 2023
The real question is how would you get as formal decription of the so called "solution" of the equality linear system?
There is no mathematical semantic AFAIK to describe the solution beside what is similar to you question, a set S that satisfies
A*x <= b
Aeq*x = beq
lo <= x <= up
One can show to linear transform the variables x to y so as the above can be reduced to the so called canonical form of
C*y = d
y <= 0
but there is no way to express it shorter.
Another way is if the region S is bounded, it is a polytope and one can express as a "sub-convex" combination of a finite set of vertexes.
S = sum wi * Vi
sum wi <= 1
In other word a convex hull where the vetices are {Vi}. There is a numerical method in FEX made by Matt J. It works OK for toy dimension of 2-3, but I wouldn't trust it for dimension >= 10.
In short the most convenient to "solve" linear inequalitues is to let it as it is. You want to know a point is a solution? Just replace and check it.
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