Let the Gram-Schmidt QR factorization of the matrix [1−2−12012−42400]\begin{bmatrix} 1 & -2 & -1 \\ 2 & 0 & 1 \\ 2 & -4 & 2 \\ 4 & 0 & 0 \end{bmatrix}1224−20−40−1120 be
What is ⌊∣a+b+c+d+e+f∣⌋%5\lfloor |a+b+c+d+e+f| \rfloor \% 5⌊∣a+b+c+d+e+f∣⌋%5? (% is the modulo operation. ⌊z⌋\lfloor z \rfloor⌊z⌋ rounds zzz to the smaller nearest integer.)
