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## cgetf2()

subroutine cgetf2 | ( | integer | m,
|  | integer | n,
|  | complex, dimension( lda, * ) | a,
|  | integer | lda,
|  | integer, dimension( * ) | ipiv,
|  | integer | info )

CGETF2 computes the LU factorization of a general m-by-n matrix using partial pivoting with row interchanges (unblocked algorithm).

Download CGETF2 + dependencies [TGZ] [ZIP] [TXT]

Purpose:

      !>
      !> CGETF2 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.
      !>

Parameters

  [in]

  M

      !>          M is INTEGER
      !>          The number of rows of the matrix A.  M >= 0.
      !>

  [in]

  N

      !>          N is INTEGER
      !>          The number of columns of the matrix A.  N >= 0.
      !>

  [in,out]

  A

      !>          A is COMPLEX 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.
      !>

  [in]

  LDA

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

  [out]

  IPIV

      !>          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).
      !>

  [out]

  INFO

      !>          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.
      !>

Author
  Univ. of Tennessee
  Univ. of California Berkeley
  Univ. of Colorado Denver
  NAG Ltd.