How to find the minimum value of $$|f(x,y)|$$ where $f(x,y)$ is a 2nd degree function in x and y with no 'xy' term. $$f(x,y)=ax^2+by^2+cx+dy+e$$ How is the process different from finding the minimum of a function without the modulus operator? See a related post: Finding minimum of a two variable 2nd degree function under a certain constraint?
Any help would be beneficial