How do i use fminsearch to find the minimum or maximum of a function . x.^4-3.*x.*y+2.*y.^2
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I trying to use fmin search for a function of 2 variable
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James Tursa
2022-10-13
编辑:James Tursa
2022-10-13
You need to have your function handle accept a vector and return a scalar. I.e., the x argument to the function handle is a vector of two elements representing your original x and y variables. Assuming x(1) and x(2) are your intended original x and y variables, that would mean something like this:
fun = @(x) x(1).^4-3.*x(1).*x(2) +2.*x(2).^2;
x0 = [-0.5,0.5];
x = fminsearch(fun,x0)
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James Tursa
2022-10-13
编辑:James Tursa
2022-10-13
format longg
fun = @(x) x(1).^4-3.*x(1).*x(2) +2.*x(2).^2;
x0 = [-0.5,0.5];
x = fminsearch(fun,x0)
fun(x)
fun([3/4,9/16])
Also note that fminsearch( ) can only find local minimums, of which there can be more than one depending on the function. So different starting points can result in different answers.
x = fminsearch(fun,[3/4+0.1,9/16-0.1])
fun(x)
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the cyclist
2022-10-13
编辑:the cyclist
2022-10-13
Did you try reading the documentation for fminsearch? The very first example is exactly like your problem.
fun = @(x)(x(1)^4 - 3*x(1)*x(2) + 2*x(2)^2);
x0 = [-0.5, 0.5];
x = fminsearch(fun,x0)
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