Hello. I have a task to find such change of variables (it should be diffeomorphism), which will transform a function to the standart Morse-type function (saddle). For example, I have a function 1/(1+x*y), which I should turn to u^2 - v^2. teacher told me, that there is a function in Wolfram Mathematica, which can do this automatically, but I can't find something like this in documentation. Please, help me. How can I solve this?
