dsptri (l)  Linux Man Pages
dsptri: computes the inverse of a real symmetric indefinite matrix A in packed storage using the factorization A = U*D*U**T or A = L*D*L**T computed by DSPTRF
Command to display dsptri
manual in Linux: $ man l dsptri
NAME
DSPTRI  computes the inverse of a real symmetric indefinite matrix A in packed storage using the factorization A = U*D*U**T or A = L*D*L**T computed by DSPTRF
SYNOPSIS
 SUBROUTINE DSPTRI(

UPLO, N, AP, IPIV, WORK, INFO )

CHARACTER
UPLO

INTEGER
INFO, N

INTEGER
IPIV( * )

DOUBLE
PRECISION AP( * ), WORK( * )
PURPOSE
DSPTRI computes the inverse of a real symmetric indefinite matrix
A in packed storage using the factorization A = U*D*U**T or
A = L*D*L**T computed by DSPTRF.
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.
 AP (input/output) DOUBLE PRECISION array, dimension (N*(N+1)/2)

On entry, the block diagonal matrix D and the multipliers
used to obtain the factor U or L as computed by DSPTRF,
stored as a packed triangular matrix.
On exit, if INFO = 0, the (symmetric) inverse of the original
matrix, stored as a packed triangular matrix. The jth column
of inv(A) is stored in the array AP as follows:
if UPLO = aqUaq, AP(i + (j1)*j/2) = inv(A)(i,j) for 1<=i<=j;
if UPLO = aqLaq,
AP(i + (j1)*(2nj)/2) = inv(A)(i,j) for j<=i<=n.
 IPIV (input) INTEGER array, dimension (N)

Details of the interchanges and the block structure of D
as determined by DSPTRF.
 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 dsptri
 dsptri (3)
 dsptrd (l)  reduces a real symmetric matrix A stored in packed form to symmetric tridiagonal form T by an orthogonal similarity transformation
 dsptrf (l)  computes the factorization of a real symmetric matrix A stored in packed format using the BunchKaufman diagonal pivoting method
 dsptrs (l)  solves a system of linear equations A*X = B with a real symmetric matrix A stored in packed format using the factorization A = U*D*U**T or A = L*D*L**T computed by DSPTRF
 dspcon (l)  estimates the reciprocal of the condition number (in the 1norm) of a real symmetric packed matrix A using the factorization A = U*D*U**T or A = L*D*L**T computed by DSPTRF
 dspev (l)  computes all the eigenvalues and, optionally, eigenvectors of a real symmetric matrix A in packed storage
 dspevd (l)  computes all the eigenvalues and, optionally, eigenvectors of a real symmetric matrix A in packed storage
 dspevx (l)  computes selected eigenvalues and, optionally, eigenvectors of a real symmetric matrix A in packed storage