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SGETRI(1) LAPACK routine (version 3.2) SGETRI(1)

NAME

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

SYNOPSIS

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

The order of the matrix A. N >= 0.
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.
The leading dimension of the array A. LDA >= max(1,N).
The pivot indices from SGETRF; for 1<=i<=N, row i of the matrix was interchanged with row IPIV(i).
On exit, if INFO=0, then WORK(1) returns the optimal LWORK.
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.
= 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.
November 2008 LAPACK routine (version 3.2)