 ITMAX*):
          = 1:  the number of iterations has reached ITMAX* without
                satisfying the convergence condition;
          = 2:  if alg = 'I' and in an iteration of the Levenberg-
                Marquardt algorithm, the CG algorithm finished
                after 3*NX iterations (or 3*(lin1-1) iterations, for
                the initialization phase), without achieving the
                precision required in the call;
          = 3:  the cosine of the angle between the vector of error
