SGETF2(3)      LAPACK routine of NEC Numeric Library Collection      SGETF2(3)



NAME
       SGETF2

SYNOPSIS
       SUBROUTINE SGETF2 (M, N, A, LDA, IPIV, INFO)



PURPOSE
            SGETF2 computes an LU factorization of a general m-by-n matrix A
            using partial pivoting with row interchanges.

            The factorization has the form
               A = P * L * U
            where P is a permutation matrix, L is lower triangular with unit
            diagonal elements (lower trapezoidal if m > n), and U is upper
            triangular (upper trapezoidal if m < n).

            This is the right-looking Level 2 BLAS version of the algorithm.




ARGUMENTS
           M         (input)
                     M is INTEGER
                     The number of rows of the matrix A.  M >= 0.

           N         (input)
                     N is INTEGER
                     The number of columns of the matrix A.  N >= 0.

           A         (input/output)
                     A is REAL array, dimension (LDA,N)
                     On entry, the m by n matrix to be factored.
                     On exit, the factors L and U from the factorization
                     A = P*L*U; the unit diagonal elements of L are not stored.

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

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

           INFO      (output)
                     INFO is INTEGER
                     = 0: successful exit
                     < 0: if INFO = -k, the k-th argument had an illegal value
                     > 0: if INFO = k, U(k,k) is exactly zero. The factorization
                          has been completed, but the factor U is exactly
                          singular, and division by zero will occur if it is used
                          to solve a system of equations.



LAPACK routine                  31 October 2017                      SGETF2(3)