Testing Gaussian Elimination Routines...

A=[[50.6958 41.9111 38.0867 34.8285]
   [-31.8004 -26.7679 -23.8605 -21.9057]
   [2.2225 1.7187 1.7229 1.6558]
   [-36.0216 -29.8725 -27.279 -24.554]]
b=[0 1 2 3]
L=[[1 0 0 0]
   [-0.627279 1 0 0]
   [-0.710544 0.194195 1 0]
   [0.0438399 0.248306 -0.204877 1]]
U=[[50.6958 41.9111 38.0867 34.8285]
   [0 -0.477956 0.030479 -0.0585207]
   [0 0 -0.22264 0.204549]
   [0 0 0 0.18536]]
P=[[1 0 0 0]
   [0 1 0 0]
   [0 0 0 1]
   [0 0 1 0]]
x=[-4.76183 -3.69733 -1.07086 12.5515]
y=[5.68434e-14 1 2 3]

The residual r=|Ax-b| is 8.03887e-14.
PASSED!