LAPACK  3.4.2
LAPACK: Linear Algebra PACKage
 All Files Functions Groups
ssptri.f File Reference

Go to the source code of this file.


subroutine ssptri (UPLO, N, AP, IPIV, WORK, INFO)

Function/Subroutine Documentation

subroutine ssptri ( character  UPLO,
integer  N,
real, dimension( * )  AP,
integer, dimension( * )  IPIV,
real, dimension( * )  WORK,
integer  INFO 


Download SSPTRI + dependencies [TGZ] [ZIP] [TXT]
 SSPTRI 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 SSPTRF.
          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.
          AP is REAL 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 SSPTRF,
          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 j-th column
          of inv(A) is stored in the array AP as follows:
          if UPLO = 'U', AP(i + (j-1)*j/2) = inv(A)(i,j) for 1<=i<=j;
          if UPLO = 'L',
             AP(i + (j-1)*(2n-j)/2) = inv(A)(i,j) for j<=i<=n.
          IPIV is INTEGER array, dimension (N)
          Details of the interchanges and the block structure of D
          as determined by SSPTRF.
          WORK is REAL array, dimension (N)
          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.
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
November 2011

Definition at line 110 of file ssptri.f.

Here is the call graph for this function:

Here is the caller graph for this function: