-------- lopcg1() -------
x0 = size 16 Vector of double:
[ -0.25 -0.25 -0.25 -0.25 -0.25 -0.25 -0.25 -0.25 -0.25 -0.25 -0.25 -0.25 -0.25 -0.25 -0.25 -0.25 ]
lambda0 = -2.36655e-18
|A*x0 - lambda0*x0| = 2.1403e-10

------- lanczos1() ------
x1 = size 16 Vector of double:
[ 0.25 -0.25 0.25 -0.25 0.25 -0.25 0.25 -0.25 0.25 -0.25 0.25 -0.25 0.25 -0.25 0.25 -0.25 ]
lambda1 = 4
A*x1 - x1*lambda1 = 1.23629e-15

