finding minimum of a nonlinear function of two variables
exact minimum: f(1, 1)=0
initial simplex:
 11 5
 5 11
 5 5
number of steps : 142
final simplex:
 1 0.999999 ; function value: 1.20661e-13
 1 1 ; function value: 1.80548e-13
 1 1 ; function value: 3.1608e-13