dsytri (l)  Linux Man Pages
dsytri: 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 DSYTRF
Command to display dsytri
manual in Linux: $ man l dsytri
NAME
DSYTRI  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 DSYTRF
SYNOPSIS
 SUBROUTINE DSYTRI(

UPLO, N, A, LDA, IPIV, WORK, INFO )

CHARACTER
UPLO

INTEGER
INFO, LDA, N

INTEGER
IPIV( * )

DOUBLE
PRECISION A( LDA, * ), WORK( * )
PURPOSE
DSYTRI 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
DSYTRF.
ARGUMENTS
 UPLO (input) CHARACTER*1

Specifies whether the details of the factorization are stored
as an upper or lower triangular matrix.
= aqUaq: Upper triangular, form is A = U*D*U**T;
= aqLaq: Lower triangular, form is A = L*D*L**T.
 N (input) INTEGER

The order of the matrix A. N >= 0.
 A (input/output) DOUBLE PRECISION 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 DSYTRF.
On exit, if INFO = 0, the (symmetric) inverse of the original
matrix. If UPLO = aqUaq, the upper triangular part of the
inverse is formed and the part of A below the diagonal is not
referenced; if UPLO = aqLaq the lower triangular part of the
inverse is formed and the part of A above the diagonal is
not referenced.
 LDA (input) INTEGER

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

Details of the interchanges and the block structure of D
as determined by DSYTRF.
 WORK (workspace) DOUBLE PRECISION array, dimension (N)

 INFO (output) INTEGER

= 0: successful exit
< 0: if INFO = i, the ith argument had an illegal value
> 0: if INFO = i, D(i,i) = 0; the matrix is singular and its
inverse could not be computed.
Pages related to dsytri
 dsytri (3)
 dsytrd (l)  reduces a real symmetric matrix A to real symmetric tridiagonal form T by an orthogonal similarity transformation
 dsytrf (l)  computes the factorization of a real symmetric matrix A using the BunchKaufman diagonal pivoting method
 dsytrs (l)  solves a system of linear equations A*X = B with a real symmetric matrix A using the factorization A = U*D*U**T or A = L*D*L**T computed by DSYTRF
 dsytd2 (l)  reduces a real symmetric matrix A to symmetric tridiagonal form T by an orthogonal similarity transformation
 dsytf2 (l)  computes the factorization of a real symmetric matrix A using the BunchKaufman diagonal pivoting method
 dsycon (l)  estimates the reciprocal of the condition number (in the 1norm) of a real symmetric matrix A using the factorization A = U*D*U**T or A = L*D*L**T computed by DSYTRF
 dsyequb (l)  computes row and column scalings intended to equilibrate a symmetric matrix A and reduce its condition number (with respect to the twonorm)