A = [1 1 1 2 2 2; 5 6 7 13 14 8; -2 1 5 2 4 -2; -1 1 2 6 12 -15; 1 3 9 -5 -5 30]
TEMP = A(1,:)
A(1,:) = A(2,:)
A(2,:) = TEMP
A(2,:) = A(2,:) - (A(2,1) / A(1,1)) * A(1,:)
 A(3,:) = A(3,:) - (A(3,1) / A(1,1)) * A(1,:)
 A(4,:) = A(4,:) - (A(4,1) / A(1,1)) * A(1,:)
  A(5,:) = A(5,:) - (A(5,1) / A(1,1)) * A(1,:)
TEMP = A(2,:)
 A(2,:) = A(3,:)
 A(3,:) = TEMP
A(3,:) = A(3,:) - (A(3,2) / A(2,2)) * A(2,:)
 A(4,:) = A(4,:) - (A(4,2) / A(2,2)) * A(2,:)
A(5,:) = A(5,:) - (A(5,2) / A(2,2)) * A(2,:)
 A(4,:) = A(4,:) - (A(4,3) / A(3,3)) * A(3,:)
A(5,:) = A(5,:) - (A(5,3) / A(3,3)) * A(3,:)
A(5,:) = A(5,:) - (A(5,4) / A(4,4)) * A(4,:)

b(5)= A(5,6) /A(5,5)
b(4) = (A(4,6) - A(4,5) * b(5))/A(4,4)
 b(3) = (A(3,6) - A(3,5) * b(5) - A(3,4) * b(4)) / A(3,3)
b(2) = (A(2,6) - A(2,5) * b(5) - A(2,4) * b(4) - A(2,3) * b(3)) / A(2,2)
 b(1) = (A(1,6) - A(1,5) * b(5) - A(1,4) * b(4) - A(1,3) * b(3) - A(1,2) * b(2)) / A(1,1)

A = [1 1 1 2 2 2; 5 6 7 13 14 8; -2 1 5 2 4 -2; -1 1 2 6 12 -15; 1 3 9 -5 -5 30]
TEMP = A(2,:)
A(2,:) = A(5,:)
 A(5,:) = TEMP
A(1,:) = A(1,:) - (A(1,5) / A(5,5)) * A(5,:)
A(2,:) = A(2,:) - (A(2,5) / A(5,5)) * A(5,:)
A(3,:) = A(3,:) - (A(3,5) / A(5,5)) * A(5,:)
A(4,:) = A(4,:) - (A(4,5) / A(5,5)) * A(5,:)
TEMP = A(1,:)
A(1,:)= A(4,:)
A(4,:) = TEMP
A(1,:) = A(1,:) - (A(1,4) / A(4,4)) * A(4,:)
A(2,:) = A(2,:) - (A(2,4) / A(4,4)) * A(4,:)
A(3,:) = A(3,:) - (A(3,4) / A(4,4)) * A(4,:)
TEMP = A(3,:)
 A(3,:) = A(2,:)
A(2,:) = TEMP
A(1,:) = A(1,:) - (A(1,3) / A(3,3)) * A(3,:)
 A(2,:) = A(2,:) - (A(2,3) / A(3,3)) * A(3,:)
TEMP = A(1,:)
A(1,:) = A(2,:)
A(2,:) = TEMP
A(1,:) = A(1,:) - (A(1,2) / A(2,2)) * A(2,:)