dsytri2.f man page

dsytri2.f —

Synopsis

Functions/Subroutines

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

Function/Subroutine Documentation

subroutine dsytri2 (characterUPLO, integerN, double precision, dimension( lda, * )A, integerLDA, integer, dimension( * )IPIV, double precision, dimension( * )WORK, integerLWORK, integerINFO)

DSYTRI2

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:

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.

N

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

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.

LDA

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

IPIV

IPIV is INTEGER array, dimension (N)
Details of the interchanges and the NB structure of D
as determined by DSYTRF.

WORK

WORK is DOUBLE PRECISION array, dimension (N+NB+1)*(NB+3)

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.

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.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

dsytri2(3) is an alias of dsytri2.f(3).

Sat Nov 16 2013 Version 3.4.2 LAPACK