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## spotri()

subroutine spotri | ( | character | uplo,
|  | integer | n,
|  | real, dimension( lda, * ) | a,
|  | integer | lda,
|  | integer | info )

SPOTRI

Download SPOTRI + dependencies [TGZ] [ZIP] [TXT]

Purpose:

      !>
      !> SPOTRI computes the inverse of a real symmetric positive definite
      !> matrix A using the Cholesky factorization A = U**T*U or A = L*L**T
      !> computed by SPOTRF.
      !>

Parameters

  [in]

  UPLO

      !>          UPLO is CHARACTER*1
      !>          = 'U':  Upper triangle of A is stored;
      !>          = 'L':  Lower triangle of A is stored.
      !>

  [in]

  N

      !>          N is INTEGER
      !>          The order of the matrix A.  N >= 0.
      !>

  [in,out]

  A

      !>          A is REAL array, dimension (LDA,N)
      !>          On entry, the triangular factor U or L from the Cholesky
      !>          factorization A = U**T*U or A = L*L**T, as computed by
      !>          SPOTRF.
      !>          On exit, the upper or lower triangle of the (symmetric)
      !>          inverse of A, overwriting the input factor U or L.
      !>

  [in]

  LDA

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

  [out]

  INFO

      !>          INFO is INTEGER
      !>          = 0:  successful exit
      !>          < 0:  if INFO = -i, the i-th argument had an illegal value
      !>          > 0:  if INFO = i, the (i,i) element of the factor U or L is
      !>                zero, and the inverse could not be computed.
      !>

Author
  Univ. of Tennessee
  Univ. of California Berkeley
  Univ. of Colorado Denver
  NAG Ltd.