CGTTS2(3)      LAPACK routine of NEC Numeric Library Collection      CGTTS2(3)



NAME
       CGTTS2

SYNOPSIS
       SUBROUTINE CGTTS2 (ITRANS, N, NRHS, DL, D, DU, DU2, IPIV, B, LDB)



PURPOSE
            CGTTS2 solves one of the systems of equations
               A * X = B,  A**T * X = B,  or  A**H * X = B,
            with a tridiagonal matrix A using the LU factorization computed
            by CGTTRF.




ARGUMENTS
           ITRANS    (input)
                     ITRANS is INTEGER
                     Specifies the form of the system of equations.
                     = 0:  A * X = B     (No transpose)
                     = 1:  A**T * X = B  (Transpose)
                     = 2:  A**H * X = B  (Conjugate transpose)

           N         (input)
                     N is INTEGER
                     The order of the matrix A.

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

           DL        (input)
                     DL is COMPLEX array, dimension (N-1)
                     The (n-1) multipliers that define the matrix L from the
                     LU factorization of A.

           D         (input)
                     D is COMPLEX array, dimension (N)
                     The n diagonal elements of the upper triangular matrix U from
                     the LU factorization of A.

           DU        (input)
                     DU is COMPLEX array, dimension (N-1)
                     The (n-1) elements of the first super-diagonal of U.

           DU2       (input)
                     DU2 is COMPLEX array, dimension (N-2)
                     The (n-2) elements of the second super-diagonal of U.

           IPIV      (input)
                     IPIV is INTEGER array, dimension (N)
                     The pivot indices; for 1 <= i <= n, row i of the matrix was
                     interchanged with row IPIV(i).  IPIV(i) will always be either
                     i or i+1; IPIV(i) = i indicates a row interchange was not
                     required.

           B         (input/output)
                     B is COMPLEX array, dimension (LDB,NRHS)
                     On entry, the matrix of right hand side vectors B.
                     On exit, B is overwritten by the solution vectors X.

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



LAPACK routine                  31 October 2017                      CGTTS2(3)