LAPACK  3.4.2
LAPACK: Linear Algebra PACKage
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dsptri.f File Reference

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

Function/Subroutine Documentation

subroutine dsptri ( character  UPLO,
integer  N,
double precision, dimension( * )  AP,
integer, dimension( * )  IPIV,
double precision, dimension( * )  WORK,
integer  INFO 


Download DSPTRI + dependencies [TGZ] [ZIP] [TXT]
 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.
          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 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 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 DSPTRF.
          WORK is DOUBLE PRECISION 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 dsptri.f.

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