This example solves the linear least squares problems for the basic solutions $x_1$ and $x_2$, where and and $b_j$ is the $j$th column of the matrix $B$. The solution is obtained by first obtaining a $QR$ factorization with column pivoting of the matrix $A$. A tolerance of $0.01$ is used to estimate the rank of $A$ from the upper triangular factor, $R$.

Note that the block size (NB) of $64$ assumed in this example is not realistic for such a small problem, but should be suitable for large problems.