exercise5:
case =  1 ||r|| =  9.999778782798785e-13 ||e|| =  1.4142135623730951
case =  2 ||r|| =  1.4142277045080116 ||e|| =  1.00000000005
case =  3 ||r|| =  281.4284989121752 ||e|| =  140.71602609511115
case =  4 ||r|| =  999999999.9998899 ||e|| =  0.0009999999999998899