Purpose

LA_GELS computes the minimum-norm least squares solution to one or more real or complex linear systems of the form $A x = b$, $A^T x = b$ or $A^H x = b$ using a $QR$ or $LQ$ factorization of A. Matrix $A$ is rectangular and assumed to be of full rank. The vectors $b$ and corresponding solution vectors $x$ are the columns of matrices denoted $B$ and $X$, respectively.