CGETC2(3)      LAPACK routine of NEC Numeric Library Collection      CGETC2(3)



NAME
       CGETC2

SYNOPSIS
       SUBROUTINE CGETC2 (N, A, LDA, IPIV, JPIV, INFO)



PURPOSE
            CGETC2 computes an LU factorization, using complete pivoting, of the
            n-by-n matrix A. The factorization has the form A = P * L * U * Q,
            where P and Q are permutation matrices, L is lower triangular with
            unit diagonal elements and U is upper triangular.

            This is a level 1 BLAS version of the algorithm.




ARGUMENTS
           N         (input)
                     N is INTEGER
                     The order of the matrix A. N >= 0.

           A         (input/output)
                     A is COMPLEX array, dimension (LDA, N)
                     On entry, the n-by-n matrix to be factored.
                     On exit, the factors L and U from the factorization
                     A = P*L*U*Q; the unit diagonal elements of L are not stored.
                     If U(k, k) appears to be less than SMIN, U(k, k) is given the
                     value of SMIN, giving a nonsingular perturbed system.

           LDA       (input)
                     LDA is INTEGER
                     The leading dimension of the array A.  LDA >= max(1, N).

           IPIV      (output)
                     IPIV is INTEGER array, dimension (N).
                     The pivot indices; for 1 <= i <= N, row i of the
                     matrix has been interchanged with row IPIV(i).

           JPIV      (output)
                     JPIV is INTEGER array, dimension (N).
                     The pivot indices; for 1 <= j <= N, column j of the
                     matrix has been interchanged with column JPIV(j).

           INFO      (output)
                     INFO is INTEGER
                      = 0: successful exit
                      > 0: if INFO = k, U(k, k) is likely to produce overflow if
                           one tries to solve for x in Ax = b. So U is perturbed
                           to avoid the overflow.



LAPACK routine                  31 October 2017                      CGETC2(3)