A system of simultaneous linear equations is written
Ax = b
where A is the coefficient matrix, b is the right hand side, and x is the solution. A is assumed to be a square matrix of order n, but some of the individual routines allow A to be rectangular. If there are several right hand sides, the system is
AX = B
where the columns of B are the individual right hand sides, and the columns of X are the corresponding solutions. The basic task is to compute X, given A and B.