To translate the steepest ascent into matlab code:

f(x,y)=-8*x + 12*y + x^2 - 2*x^4 - 2*x*y + 4*y^2

dx=-8+2x-8x^3-2y

dy=12-2x+8y

subs in x0=0, y0=0 into dx and dy

dx=-8

dy=12

subs dx and dy into x1=x0 + dx*0.001 and y1=y0 + dy*0.001

then subs x1 and y1 back to x0 and x0; repeat the step until the answer has reach optimisation.