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## zgetri()

subroutine zgetri | ( | integer | n,
|  | complex*16, dimension( lda, * ) | a,
|  | integer | lda,
|  | integer, dimension( * ) | ipiv,
|  | complex*16, dimension( * ) | work,
|  | integer | lwork,
|  | integer | info )

ZGETRI

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

Purpose:

      !>
      !> ZGETRI computes the inverse of a matrix using the LU factorization
      !> computed by ZGETRF.
      !>
      !> This method inverts U and then computes inv(A) by solving the system
      !> inv(A)*L = inv(U) for inv(A).
      !>

Parameters

  [in]

  N

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

  [in,out]

  A

      !>          A is COMPLEX*16 array, dimension (LDA,N)
      !>          On entry, the factors L and U from the factorization
      !>          A = P*L*U as computed by ZGETRF.
      !>          On exit, if INFO = 0, the inverse of the original matrix A.
      !>

  [in]

  LDA

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

  [in]

  IPIV

      !>          IPIV is INTEGER array, dimension (N)
      !>          The pivot indices from ZGETRF; for 1<=i<=N, row i of the
      !>          matrix was interchanged with row IPIV(i).
      !>

  [out]

  WORK

      !>          WORK is COMPLEX*16 array, dimension (MAX(1,LWORK))
      !>          On exit, if INFO=0, then WORK(1) returns the optimal LWORK.
      !>

  [in]

  LWORK

      !>          LWORK is INTEGER
      !>          The dimension of the array WORK.  LWORK >= max(1,N).
      !>          For optimal performance LWORK >= N*NB, where NB is
      !>          the optimal blocksize returned by ILAENV.
      !>
      !>          If LWORK = -1, then a workspace query is assumed; the routine
      !>          only calculates the optimal size of the WORK array, returns
      !>          this value as the first entry of the WORK array, and no error
      !>          message related to LWORK is issued by XERBLA.
      !>

  [out]

  INFO

      !>          INFO is INTEGER
      !>          = 0:  successful exit
      !>          < 0:  if INFO = -i, the i-th argument had an illegal value
      !>          > 0:  if INFO = i, U(i,i) is exactly zero; the matrix is
      !>                singular and its inverse could not be computed.
      !>

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