CPTTS2  - solve a tridiagonal system of the form A * X = B
       using the factorization A = U'*D*U or A = L*D*L'  computed
       by CPTTRF


SYNOPSIS

       SUBROUTINE CPTTS2( IUPLO, N, NRHS, D, E, B, LDB )

           INTEGER        IUPLO, LDB, N, NRHS

           REAL           D( * )

           COMPLEX        B( LDB, * ), E( * )


PURPOSE

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


ARGUMENTS

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

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

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

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

       E       (input) COMPLEX array, dimension (N-1)
               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) 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.

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


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