The directions of the axes for the function in #4 f(x,y)=(2*x-y)^2+(1+y)^2 are given by <1,1/2+sqrt(5)/2> and <1,1/2-sqrt(5)/2>, which are uglier than I thought they would be. These are needed for #7 part 2.
Descenting the f(x,y) = x^2-x*y+y^2 valley
A short table of the approximations i, x_i, y_i, z_i, [0, 1, 0, 1], [1, 2/7, 5/14, 3/28], [2, 3/28, 0, 9/784], [3, 3/98, 15/392, 27/21952], [4, 9/784, 0, 81/614656], [5, 9/2744, 45/10976, 243/17210368],
Here is a collection ti-89 commands which does similar calculations for steepest descent