ssytri (l)  Linux Manuals
ssytri: 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 SSYTRF
Command to display ssytri
manual in Linux: $ man l ssytri
NAME
SSYTRI  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 SSYTRF
SYNOPSIS
 SUBROUTINE SSYTRI(

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

CHARACTER
UPLO

INTEGER
INFO, LDA, N

INTEGER
IPIV( * )

REAL
A( LDA, * ), WORK( * )
PURPOSE
SSYTRI 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
SSYTRF.
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) REAL 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 SSYTRF.
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 SSYTRF.
 WORK (workspace) REAL 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 ssytri
 ssytri (3)
 ssytrd (l)  reduces a real symmetric matrix A to real symmetric tridiagonal form T by an orthogonal similarity transformation
 ssytrf (l)  computes the factorization of a real symmetric matrix A using the BunchKaufman diagonal pivoting method
 ssytrs (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 SSYTRF
 ssytd2 (l)  reduces a real symmetric matrix A to symmetric tridiagonal form T by an orthogonal similarity transformation
 ssytf2 (l)  computes the factorization of a real symmetric matrix A using the BunchKaufman diagonal pivoting method
 ssycon (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 SSYTRF
 ssyequb (l)  computes row and column scalings intended to equilibrate a symmetric matrix A and reduce its condition number (with respect to the twonorm)