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  man pages->IRIX man pages -> complib/dgetri (3)              
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DGETRI(3F)							    DGETRI(3F)


NAME    [Toc]    [Back]

     DGETRI - compute the inverse of a matrix using the	LU factorization
     computed by DGETRF

SYNOPSIS    [Toc]    [Back]

     SUBROUTINE	DGETRI(	N, A, LDA, IPIV, WORK, LWORK, INFO )

	 INTEGER	INFO, LDA, LWORK, N

	 INTEGER	IPIV( *	)

	 DOUBLE		PRECISION A( LDA, * ), WORK( LWORK )

PURPOSE    [Toc]    [Back]

     DGETRI computes the inverse of a matrix using the LU factorization
     computed by DGETRF.

     This method inverts U and then computes inv(A) by solving the system
     inv(A)*L =	inv(U) for inv(A).

ARGUMENTS    [Toc]    [Back]

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

     A	     (input/output) DOUBLE PRECISION array, dimension (LDA,N)
	     On	entry, the factors L and U from	the factorization A = P*L*U as
	     computed by DGETRF.  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 DGETRF; for	1<=i<=N, row i of the matrix
	     was interchanged with row IPIV(i).

     WORK    (workspace/output)	DOUBLE PRECISION 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.

     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.
DGETRI(3F)							    DGETRI(3F)


NAME    [Toc]    [Back]

     DGETRI - compute the inverse of a matrix using the	LU factorization
     computed by DGETRF

SYNOPSIS    [Toc]    [Back]

     SUBROUTINE	DGETRI(	N, A, LDA, IPIV, WORK, LWORK, INFO )

	 INTEGER	INFO, LDA, LWORK, N

	 INTEGER	IPIV( *	)

	 DOUBLE		PRECISION A( LDA, * ), WORK( LWORK )

PURPOSE    [Toc]    [Back]

     DGETRI computes the inverse of a matrix using the LU factorization
     computed by DGETRF.

     This method inverts U and then computes inv(A) by solving the system
     inv(A)*L =	inv(U) for inv(A).

ARGUMENTS    [Toc]    [Back]

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

     A	     (input/output) DOUBLE PRECISION array, dimension (LDA,N)
	     On	entry, the factors L and U from	the factorization A = P*L*U as
	     computed by DGETRF.  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 DGETRF; for	1<=i<=N, row i of the matrix
	     was interchanged with row IPIV(i).

     WORK    (workspace/output)	DOUBLE PRECISION 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.

     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.


									PPPPaaaaggggeeee 1111
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