find minimum of a function when x>0 in matlab

You can use the fminbnd function in MATLAB to find the minimum of a function when x>0. This function takes a function to be minimized and a search interval as inputs, and returns the minimum value and the location of the minimum.

Here's an example:

main.m
f = @(x) x^2 - 4*x + 3; % define the function
[xmin, fmin] = fminbnd(f, 0, Inf); % find the minimum when x>0
disp(xmin);
disp(fmin);
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In this example, we're finding the minimum of the function f(x) = x^2 - 4x + 3 when x>0. The @ symbol is used to create a function handle to f, which allows us to pass the f function as an argument to fminbnd. The search interval is set from 0 to Inf to restrict the search to values of x that are greater than 0.

The output of the fminbnd function is the location of the minimum, xmin, and the minimum function value, fmin. These values are then displayed using the disp function.

Note that fminbnd requires a smooth function, so it may not work for all types of functions. If you have a non-smooth function, you may need to use a different optimization function.