Find the best frequency range to maximize Phase Margin

Hello! I am trying to find the best frequency from a range between x and y to maximize the phase margin of a system. I want to have matlab run through a range of frequencies and then find the frequency in that set that would find the max phase margin. I am thinking this might have to do with the find command and a for loop but im not certain

[madhan ravi]

You can use loop for plotting and then guess the exact frequency by using data cursor ?