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mathmatlabsymbolic-math

How to solve equality equation through matlab solver?

I have a question related to basic mathematics, but with Matlab solving method. Here is the question:

y = 5;

for x=0.01:100
    F = 3*x + y - 2*x^2;
end

From the above iterative equation I want to find the max [F] value and its relative [x]. Is it possible to solve it through matlab solvers. Could you please help me to solve this problem?

Solution

  • For unconstrained non-linear optimization (according to your last edit) use fminsearch to solve your problem. It would be something like this:

    F = @(x) 3*x + y - 2*x^2;
xini = 5; %initial value to the solver
[xsolu Fsolu] = fminsearch(@F,xini)

    To control the options, parameters of solver see optimset

    opts = optimset('MaxFunEvals',10e4, 'MaxIter', 10e4)
[xsolu Fsolu] = fminsearch(@F,xini, opts)

    The solution according to your original formulation would be:

    x=0.01:100;
F = zeros(length(x),1);
for ii = 1:length(x)
    F(i) = 3*x(i) + y - 2*x(i)^2;
end

xsolu = max(F);
Fsolu = F(x == xsolu);

    Which is quite inefficient approach, to say nothing more.