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.

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).

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