ptts2(3)

NAME
ptts2 - ptts2: triangular solve using factor, unblocked

SYNOPSIS

  Functions

subroutine cptts2 (iuplo, n, nrhs, d, e, b, ldb)
CPTTS2 solves a tridiagonal system of the form AX=B using the L D LH factorization computed by spttrf.
subroutine dptts2 (n, nrhs, d, e, b, ldb)
DPTTS2 solves a tridiagonal system of the form AX=B using the L D LH factorization computed by spttrf.
subroutine sptts2 (n, nrhs, d, e, b, ldb)
SPTTS2 solves a tridiagonal system of the form AX=B using the L D LH factorization computed by spttrf.
subroutine zptts2 (iuplo, n, nrhs, d, e, b, ldb)
ZPTTS2 solves a tridiagonal system of the form AX=B using the L D LH factorization computed by spttrf.

Detailed Description

Function Documentation

  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.

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
    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
    !>

    N

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

    NRHS

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

    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.
    !>

    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.
    !>

    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.
    !>

    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.

  subroutine dptts2 (integer n, integer nrhs, double precision, dimension( * ) d, double precision, dimension( * ) e, double precision, dimension( ldb, * ) b, integer ldb)

DPTTS2 solves a tridiagonal system of the form AX=B using the L D LH factorization computed by spttrf.

Purpose:

    !>
    !> DPTTS2 solves a tridiagonal system of the form
    !>    A * X = B
    !> using the L*D*L**T factorization of A computed by DPTTRF.  D is a
    !> diagonal matrix specified in the vector D, L is a unit bidiagonal
    !> matrix whose subdiagonal is specified in the vector E, and X and B
    !> are N by NRHS matrices.
    !>

Parameters
    N

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

    NRHS

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

    D

    !>          D is DOUBLE PRECISION array, dimension (N)
    !>          The n diagonal elements of the diagonal matrix D from the
    !>          L*D*L**T factorization of A.
    !>

    E

    !>          E is DOUBLE PRECISION array, dimension (N-1)
    !>          The (n-1) subdiagonal elements of the unit bidiagonal factor
    !>          L from the L*D*L**T factorization of A.  E can also be regarded
    !>          as the superdiagonal of the unit bidiagonal factor U from the
    !>          factorization A = U**T*D*U.
    !>

    B

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

    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.

  subroutine sptts2 (integer n, integer nrhs, real, dimension( * ) d, real, dimension( * ) e, real, dimension( ldb, * ) b, integer ldb)

SPTTS2 solves a tridiagonal system of the form AX=B using the L D LH factorization computed by spttrf.

Purpose:

    !>
    !> SPTTS2 solves a tridiagonal system of the form
    !>    A * X = B
    !> using the L*D*L**T factorization of A computed by SPTTRF.  D is a
    !> diagonal matrix specified in the vector D, L is a unit bidiagonal
    !> matrix whose subdiagonal is specified in the vector E, and X and B
    !> are N by NRHS matrices.
    !>

Parameters
    N

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

    NRHS

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

    D

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

    E

    !>          E is REAL array, dimension (N-1)
    !>          The (n-1) subdiagonal elements of the unit bidiagonal factor
    !>          L from the L*D*L**T factorization of A.  E can also be regarded
    !>          as the superdiagonal of the unit bidiagonal factor U from the
    !>          factorization A = U**T*D*U.
    !>

    B

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

    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.

  subroutine zptts2 (integer iuplo, integer n, integer nrhs, double precision, dimension( * ) d, complex*16, dimension( * ) e, complex*16, dimension( ldb, * ) b, integer ldb)

ZPTTS2 solves a tridiagonal system of the form AX=B using the L D LH factorization computed by spttrf.

Purpose:

    !>
    !> ZPTTS2 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 ZPTTRF.
    !> 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
    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
    !>

    N

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

    NRHS

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

    D

    !>          D is DOUBLE PRECISION 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.
    !>

    E

    !>          E is COMPLEX*16 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.
    !>

    B

    !>          B is COMPLEX*16 array, dimension (LDB,NRHS)
    !>          On entry, the right hand side vectors B for the system of
    !>          linear equations.
    !>          On exit, the solution vectors, X.
    !>

    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.

Author

Generated automatically by Doxygen for LAPACK from the source code.