csytri2-f(3)

csytri2.f –

Synopsis

Functions/Subroutines

subroutine csytri2 (UPLO, N, A, LDA, IPIV, WORK, LWORK, INFO)
CSYTRI2

Function/Subroutine Documentation

subroutine csytri2 (characterUPLO, integerN, complex, dimension( lda, * )A, integerLDA, integer, dimension( * )IPIV, complex, dimension( * )WORK, integerLWORK, integerINFO)

CSYTRI2

Purpose:

 CSYTRI2 computes the inverse of a COMPLEX symmetric indefinite matrix
 A using the factorization A = U*D*U**T or A = L*D*L**T computed by
 CSYTRF. CSYTRI2 sets the LEADING DIMENSION of the workspace
 before calling CSYTRI2X 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 is INTEGER
 The order of the matrix A. N >= 0.

 A is COMPLEX 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 CSYTRF.
 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 CSYTRF.

WORK

 WORK is COMPLEX 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 csytri2.f.

Author

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