CGTTS2(3)                  MathKeisan LAPACK routine                 CGTTS2(3)



NAME
       CGTTS2  -  one of the systems of equations  A * X = B, A**T * X = B, or
       A**H * X = B,

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

           INTEGER        ITRANS, LDB, N, NRHS

           INTEGER        IPIV( * )

           COMPLEX        B( LDB, * ), D( * ), DL( * ), DU( * ), DU2( * )

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) 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) INTEGER
               The order of the matrix A.

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

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

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

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

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

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



 LAPACK auxiliary routine (versionNo3v.e1m)ber 2006                       CGTTS2(3)