sgetri(l) [redhat man page]

SGETRI(l)								 )								 SGETRI(l)

NAME

       SGETRI - compute the inverse of a matrix using the LU factorization computed by SGETRF

SYNOPSIS

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

	   INTEGER	  INFO, LDA, LWORK, N

	   INTEGER	  IPIV( * )

	   REAL 	  A( LDA, * ), WORK( * )

PURPOSE

       SGETRI  computes  the inverse of a matrix using the LU factorization computed by SGETRF.  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) REAL array, dimension (LDA,N)
	       On entry, the factors L and U from the factorization A = P*L*U as computed by SGETRF.  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 SGETRF; for 1<=i<=N, row i of the matrix was interchanged with row IPIV(i).

       WORK    (workspace/output) REAL 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.

LAPACK version 3.0						   15 June 2000 							 SGETRI(l)

sgetri.f(3)							      LAPACK							       sgetri.f(3)

NAME

       sgetri.f -

SYNOPSIS

   Functions/Subroutines
       subroutine sgetri (N, A, LDA, IPIV, WORK, LWORK, INFO)
	   SGETRI

Function/Subroutine Documentation
   subroutine sgetri (integerN, real, dimension( lda, * )A, integerLDA, integer, dimension( * )IPIV, real, dimension( * )WORK, integerLWORK,
       integerINFO)
       SGETRI

       Purpose:

	    SGETRI computes the inverse of a matrix using the LU factorization
	    computed by SGETRF.

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

       Parameters:
	   N

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

	   A

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

	   LDA

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

	   IPIV

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

	   WORK

		     WORK is REAL array, dimension (MAX(1,LWORK))
		     On exit, if INFO=0, then WORK(1) returns the optimal LWORK.

	   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.

	   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.

       Date:
	   November 2011

       Definition at line 115 of file sgetri.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.2							  Tue Sep 25 2012						       sgetri.f(3)