Do you have the optimization toolbox?
To start you can begin with the fminbnd function. For example, say your function is g(x) = -x^2*exp(-x) for 0<x<10. You can find the minimum of the function on the specified interval using the commands
% define a function handle
g = @(x) -x.^2.*exp(-x);
% find minimum on specified interval
[xMin,fVal] = fminbnd(g,0,10);
% visualize
t = linspace(0,10);
plot(t,g(t),xMin,fVal,'ro')
