Solving Inequalities using symbolic tool box
61 views (last 30 days)
Show older comments
When I try to solve simple inequality
let say
the solution is
but matlab is giving wierd answers
syms x
solve(x^2 - 25>0,x)
can somone help me, how to fix this issue?
2 Comments
Torsten
on 28 Oct 2023
syms x real
sol = solve(x^2 - 25>0,x,'ReturnConditions',1);
sol.x(1)
sol.x(2)
sol.conditions
Answers (1)
Walter Roberson
on 31 Oct 2023
It is common with the symbolic engine that in practice you need to convert inequalities into equalities by introducing a non-negative or a positive "excess" variable -- so if f(x) > y(x) then f(x) - y(x) > 0; let δ quantify how much more so f(x) - y(x) = delta for positive delta. Now you can try to solve() your system for the other variables and you will get back a system of solutions in terms of the quantified-excess variables
1 Comment
Walter Roberson
on 31 Oct 2023
syms x real
syms delta positive
eqn = x^2 - 25 == delta %amount difference of terms is greater than 0
sol = solve(eqn, x)
See Also
Categories
Find more on Assumptions in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!