Visible to Intel only — GUID: GUID-1576D150-4AD0-4CAF-BD65-F4EE78F9BCDC
Visible to Intel only — GUID: GUID-1576D150-4AD0-4CAF-BD65-F4EE78F9BCDC
?sytri2
Computes the inverse of a symmetric indefinite matrix through setting the leading dimension of the workspace and calling ?sytri2x.
Syntax
call ssytri2( uplo, n, a, lda, ipiv, work, lwork, info )
call dsytri2( uplo, n, a, lda, ipiv, work, lwork, info )
call csytri2( uplo, n, a, lda, ipiv, work, lwork, info )
call zsytri2( uplo, n, a, lda, ipiv, work, lwork, info )
call sytri2( a,ipiv[,uplo][,info] )
Include Files
- mkl.fi, lapack.f90
Description
The routine computes the inverse inv(A) of a symmetric indefinite matrix A using the factorization A = U*D*UT or A = L*D*LT computed by ?sytrf.
The ?sytri2 routine sets the leading dimension of the workspace before calling ?sytri2x that actually computes the inverse.
Input Parameters
uplo |
CHARACTER*1. Must be 'U' or 'L'. Indicates how the input matrix A has been factored: If uplo = 'U', the array a stores the factorization A = U*D*UT. If uplo = 'L', the array a stores the factorization A = L*D*LT. |
n |
INTEGER. The order of the matrix A; n≥ 0. |
a, work |
REAL for ssytri2 DOUBLE PRECISION for dsytri2 COMPLEX for csytri2 DOUBLE COMPLEX for zsytri2 Array a(size lda by n) contains the block diagonal matrix D and the multipliers used to obtain the factor U or L as returned by ?sytrf. The second dimension of a must be at least max(1,n). work is a workspace array of (n+nb+1)*(nb+3) dimension. |
lda |
INTEGER. The leading dimension of a; lda≥ max(1, n). |
ipiv |
INTEGER. Array, size at least max(1, n). Details of the interchanges and the block structure of D as returned by ?sytrf. |
lwork |
INTEGER. The dimension of the work array. lwork≥ (n+nb+1)*(nb+3) where nb is the block size parameter as returned by sytrf. 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. |
Output Parameters
a |
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. |
info |
INTEGER. If info = 0, the execution is successful. If info =-i, the i-th parameter had an illegal value. If info = i, D(i,i) = 0; D is singular and its inversion could not be computed. |
LAPACK 95 Interface Notes
Routines in Fortran 95 interface have fewer arguments in the calling sequence than their FORTRAN 77 counterparts. For general conventions applied to skip redundant or reconstructible arguments, see LAPACK 95 Interface Conventions.
Specific details for the routine sytri2 interface are as follows:
a |
Holds the matrix A of size (n,n). |
ipiv |
Holds the vector of length n. |
uplo |
Indicates how the matrix A has been factored. Must be 'U' or 'L'. |