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dsytri2.f File Reference

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Functions/Subroutines

subroutine dsytri2 (UPLO, N, A, LDA, IPIV, WORK, LWORK, INFO)
 DSYTRI2 More...
 

Function/Subroutine Documentation

subroutine dsytri2 ( character  UPLO,
integer  N,
double precision, dimension( lda, * )  A,
integer  LDA,
integer, dimension( * )  IPIV,
double precision, dimension( * )  WORK,
integer  LWORK,
integer  INFO 
)

DSYTRI2

Download DSYTRI2 + dependencies [TGZ] [ZIP] [TXT]

Purpose:
 DSYTRI2 computes the inverse of a DOUBLE PRECISION symmetric indefinite matrix
 A using the factorization A = U*D*U**T or A = L*D*L**T computed by
 DSYTRF. DSYTRI2 sets the LEADING DIMENSION of the workspace
 before calling DSYTRI2X that actually computes the inverse.
Parameters
[in]UPLO
          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.
[in]N
          N is INTEGER
          The order of the matrix A.  N >= 0.
[in,out]A
          A is DOUBLE PRECISION array, dimension (LDA,N)
          On entry, the NB diagonal matrix D and the multipliers
          used to obtain the factor U or L as computed by DSYTRF.

          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.
[in]LDA
          LDA is INTEGER
          The leading dimension of the array A.  LDA >= max(1,N).
[in]IPIV
          IPIV is INTEGER array, dimension (N)
          Details of the interchanges and the NB structure of D
          as determined by DSYTRF.
[out]WORK
          WORK is DOUBLE PRECISION array, dimension (N+NB+1)*(NB+3)
[in]LWORK
          LWORK is INTEGER
          The dimension of the array WORK.
          WORK is size >= (N+NB+1)*(NB+3)
          If LDWORK = -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 LDWORK is issued by XERBLA.
[out]INFO
          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.
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date
September 2012

Definition at line 128 of file dsytri2.f.

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