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LAPACK version 3.0
zgetri(3)

PURPOSE
  ZGETRI - compute the inverse of a matrix using the LU factorization
  computed by ZGETRF

SYNTAX
  SUBROUTINE ZGETRI( N, A, LDA, IPIV, WORK, LWORK, INFO )

      INTEGER	     INFO, LDA, LWORK, N

      INTEGER	     IPIV( * )

      COMPLEX*16     A( LDA, * ), WORK( * )

DESCRIPTION
  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).

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

  A	  (input/output) 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.

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

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

  WORK	  (workspace/output) COMPLEX*16 array, dimension (LWORK)
	  On exit, if INFO=0, then WORK(1) returns the optimal LWORK.

  LWORK	  (input) 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.

  INFO	  (output) 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.