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## dpptrs()

subroutine dpptrs | ( | character | uplo,
|  | integer | n,
|  | integer | nrhs,
|  | double precision, dimension( * ) | ap,
|  | double precision, dimension( ldb, * ) | b,
|  | integer | ldb,
|  | integer | info )

DPPTRS

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

Purpose:

      !>
      !> DPPTRS solves a system of linear equations A*X = B with a symmetric
      !> positive definite matrix A in packed storage using the Cholesky
      !> factorization A = U**T*U or A = L*L**T computed by DPPTRF.
      !>

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]

  NRHS

      !>          NRHS is INTEGER
      !>          The number of right hand sides, i.e., the number of columns
      !>          of the matrix B.  NRHS >= 0.
      !>

  [in]

  AP

      !>          AP is DOUBLE PRECISION array, dimension (N*(N+1)/2)
      !>          The triangular factor U or L from the Cholesky factorization
      !>          A = U**T*U or A = L*L**T, packed columnwise in a linear
      !>          array.  The j-th column of U or L is stored in the array AP
      !>          as follows:
      !>          if UPLO = 'U', AP(i + (j-1)*j/2) = U(i,j) for 1<=i<=j;
      !>          if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = L(i,j) for j<=i<=n.
      !>

  [in,out]

  B

      !>          B is DOUBLE PRECISION array, dimension (LDB,NRHS)
      !>          On entry, the right hand side matrix B.
      !>          On exit, the solution matrix X.
      !>

  [in]

  LDB

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

  [out]

  INFO

      !>          INFO is INTEGER
      !>          = 0:  successful exit
      !>          < 0:  if INFO = -i, the i-th argument had an illegal value
      !>

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