Contents

• NAME
• SYNOPSIS
  • F95 INTERFACE
  • C INTERFACE
• PURPOSE
• ARGUMENTS

NAME

     zptts2 - solve a tridiagonal system of the form  A * X  =  B
     using the factorization A = U'*D*U or A = L*D*L' computed by
     ZPTTRF

SYNOPSIS

     SUBROUTINE ZPTTS2(IUPLO, N, NRHS, D, E, B, LDB)

     DOUBLE COMPLEX E(*), B(LDB,*)
     INTEGER IUPLO, N, NRHS, LDB
     DOUBLE PRECISION D(*)

     SUBROUTINE ZPTTS2_64(IUPLO, N, NRHS, D, E, B, LDB)

     DOUBLE COMPLEX E(*), B(LDB,*)
     INTEGER*8 IUPLO, N, NRHS, LDB
     DOUBLE PRECISION D(*)

  F95 INTERFACE
     SUBROUTINE ZPTTS2(IUPLO, N, NRHS, D, E, B, LDB)

     COMPLEX(8), DIMENSION(:) :: E
     COMPLEX(8), DIMENSION(:,:) :: B
     INTEGER :: IUPLO, N, NRHS, LDB
     REAL(8), DIMENSION(:) :: D

     SUBROUTINE ZPTTS2_64(IUPLO, N, NRHS, D, E, B, LDB)

     COMPLEX(8), DIMENSION(:) :: E
     COMPLEX(8), DIMENSION(:,:) :: B
     INTEGER(8) :: IUPLO, N, NRHS, LDB
     REAL(8), DIMENSION(:) :: D

  C INTERFACE
     #include <sunperf.h>

     void zptts2(int iuplo, int n, int  nrhs,  double  *d,  doub-
               lecomplex *e, doublecomplex *b, int ldb);

     void zptts2_64(long iuplo, long n,  long  nrhs,  double  *d,
               doublecomplex *e, doublecomplex *b, long ldb);

PURPOSE

     zptts2 solves a tridiagonal system of the form
        A * X = B using the factorization  A  =  U'*D*U  or  A  =
     L*D*L' 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.

ARGUMENTS

     IUPLO (input)
               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'*D*U,
               E is the superdiagonal of U
               = 0:  A = L*D*L', E is the subdiagonal of L

     N (input) The order of the tridiagonal matrix A.  N >= 0.

     NRHS (input)
               The number of right hand sides, i.e.,  the  number
               of columns of the matrix B.  NRHS >= 0.

     D (input) The n diagonal elements of the diagonal  matrix  D
               from the factorization A = U'*D*U or A = L*D*L'.

     E (input) If IUPLO = 1, the (n-1) superdiagonal elements  of
               the  unit  bidiagonal factor U from the factoriza-
               tion A = U'*D*U.  If IUPLO = 0, the (n-1) subdiag-
               onal elements of the unit bidiagonal factor L from
               the factorization A = L*D*L'.

     B (input/output)
               On entry, the right hand side vectors  B  for  the
               system of linear equations.  On exit, the solution
               vectors, X.

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