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## dlauu2()

subroutine dlauu2 | ( | character | uplo,
|  | integer | n,
|  | double precision, dimension( lda, * ) | a,
|  | integer | lda,
|  | integer | info )

DLAUU2 computes the product UUH or LHL, where U and L are upper or lower triangular matrices (unblocked algorithm).

Download DLAUU2 + dependencies [TGZ] [ZIP] [TXT]

Purpose:

      !>
      !> DLAUU2 computes the product U * U**T or L**T * L, where the triangular
      !> factor U or L is stored in the upper or lower triangular part of
      !> the array A.
      !>
      !> If UPLO = 'U' or 'u' then the upper triangle of the result is stored,
      !> overwriting the factor U in A.
      !> If UPLO = 'L' or 'l' then the lower triangle of the result is stored,
      !> overwriting the factor L in A.
      !>
      !> This is the unblocked form of the algorithm, calling Level 2 BLAS.
      !>

Parameters

  [in]

  UPLO

      !>          UPLO is CHARACTER*1
      !>          Specifies whether the triangular factor stored in the array A
      !>          is upper or lower triangular:
      !>          = 'U':  Upper triangular
      !>          = 'L':  Lower triangular
      !>

  [in]

  N

      !>          N is INTEGER
      !>          The order of the triangular factor U or L.  N >= 0.
      !>

  [in,out]

  A

      !>          A is DOUBLE PRECISION array, dimension (LDA,N)
      !>          On entry, the triangular factor U or L.
      !>          On exit, if UPLO = 'U', the upper triangle of A is
      !>          overwritten with the upper triangle of the product U * U**T;
      !>          if UPLO = 'L', the lower triangle of A is overwritten with
      !>          the lower triangle of the product L**T * 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 = -k, the k-th argument had an illegal value
      !>

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