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template<typename T>
void sytri2(char *uplo, integer *n, T *a, integer *lda, integer *ipiv, T *work, integer *lwork, integer *info)# SYTRI2 computes the inverse of a REAL symmetric indefinite matrix
A using the factorization.
Purpose:
SYTRI2 computes the inverse of a REAL symmetric indefinite matrix A using the factorization A = U*D*U**T or A = L*D*L**T computed by SYTRF. SYTRI2 sets the LEADING DIMENSION of the workspace before calling SYTRI2X that actually computes the inverse.
- Parameters:
UPLO – [in]
UPLO is CHARACTER*1
Specifies whether the details of the factorization are stored as an upper or lower triangular matrix.
= ‘U’: Upper triangular, form is A = U*D*U**T;
= ‘L’: Lower triangular, form is A = L*D*L**T.
N – [in]
N is INTEGER
The order of the matrix A. N >= 0.
A – [inout]
A is REAL array, dimension (LDA,N)
On entry, the block diagonal matrix D and the multipliers used to obtain the factor U or L as computed by SSYTRF.
On exit, if INFO = 0, the (symmetric) inverse of the original matrix. If UPLO = ‘U’, the upper triangular part of the inverse is formed and the part of A below the diagonal is not referenced; if UPLO = ‘L’ the lower triangular part of the inverse is formed and the part of A above the diagonal is not referenced.LDA – [in]
LDA is INTEGER
The leading dimension of the array A. LDA >= fla_max(1,N).
IPIV – [in]
IPIV is INTEGER array, dimension (N)
Details of the interchanges and the block structure of D as determined by SYTRF.
WORK – [out] WORK is REAL array, dimension (N+NB+1)*(NB+3)
LWORK – [in]
LWORK is INTEGER
The dimension of the array WORK. WORK is size >= (N+NB+1)*(NB+3)
If LWORK = -1, then a workspace query is assumed; the routine 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 – [out]
INFO is INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
> 0: if INFO = i, D(i,i) = 0; the matrix is singular and its inverse could not be computed.