Fitting values with polyfit in Matlab

Question

I have made some measurements with tic-toc of X=qr(A) and [Q,R]=qr(A), where A is a random matrix, with dimensions nxn (n=[100:100:1000]).

Now I want to create a function that describes the time measurements i have made. I want the polynomial to be cubic and i want to use the polyfit function for creating it. Though, i can't understand what arguments to pass to polyfit. The last argument will be 3 (cubic), but what should the other two arguments be?

Answer 1

n is the first argument, and the time is the second. Both should be with the same length