Loading...
Searching...
No Matches

## cptts2()

subroutine cptts2 | ( | integer | iuplo,
|  | integer | n,
|  | integer | nrhs,
|  | real, dimension( * ) | d,
|  | complex, dimension( * ) | e,
|  | complex, dimension( ldb, * ) | b,
|  | integer | ldb )

CPTTS2 solves a tridiagonal system of the form AX=B using the L D LH factorization computed by spttrf.

Download CPTTS2 + dependencies [TGZ] [ZIP] [TXT]

Purpose:

      !>
      !> CPTTS2 solves a tridiagonal system of the form
      !>    A * X = B
      !> using the factorization A = U**H*D*U or A = L*D*L**H computed by CPTTRF.
      !> D is a diagonal matrix specified in the vector D, U (or L) is a unit
      !> bidiagonal matrix whose superdiagonal (subdiagonal) is specified in
      !> the vector E, and X and B are N by NRHS matrices.
      !>

Parameters

  [in]

  IUPLO

      !>          IUPLO is INTEGER
      !>          Specifies the form of the factorization and whether the
      !>          vector E is the superdiagonal of the upper bidiagonal factor
      !>          U or the subdiagonal of the lower bidiagonal factor L.
      !>          = 1:  A = U**H *D*U, E is the superdiagonal of U
      !>          = 0:  A = L*D*L**H, E is the subdiagonal of L
      !>

  [in]

  N

      !>          N is INTEGER
      !>          The order of the tridiagonal 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]

  D

      !>          D is REAL array, dimension (N)
      !>          The n diagonal elements of the diagonal matrix D from the
      !>          factorization A = U**H *D*U or A = L*D*L**H.
      !>

  [in]

  E

      !>          E is COMPLEX array, dimension (N-1)
      !>          If IUPLO = 1, the (n-1) superdiagonal elements of the unit
      !>          bidiagonal factor U from the factorization A = U**H*D*U.
      !>          If IUPLO = 0, the (n-1) subdiagonal elements of the unit
      !>          bidiagonal factor L from the factorization A = L*D*L**H.
      !>

  [in,out]

  B

      !>          B is COMPLEX array, dimension (LDB,NRHS)
      !>          On entry, the right hand side vectors B for the system of
      !>          linear equations.
      !>          On exit, the solution vectors, X.
      !>

  [in]

  LDB

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

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