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

SYNOPSIS
     SUBROUTINE ZGTTRS( TRANS, N, NRHS, DL, D, DU, DU2, IPIV,  B,
               LDB, INFO )

     CHARACTER TRANS

     INTEGER INFO, LDB, N, NRHS

     INTEGER IPIV( * )

     COMPLEX*16 B( LDB, * ), D( * ), DL( * ), DU( * ), DU2( * )



     #include <sunperf.h>

     void zgttrs(char trans, int n, int nrhs, doublecomplex  *dl,
               doublecomplex *d, doublecomplex *du, doublecomplex
               *du2, int *ipivot, doublecomplex *zb, int ldb, int
               *info) ;

PURPOSE
     ZGTTRS solves one of the systems of equations
        A * X = B,  A**T * X = B,  or  A**H * X = B, with a  tri-
     diagonal  matrix  A  using  the LU factorization computed by
     ZGTTRF.


ARGUMENTS
     TRANS     (input) CHARACTER
               Specifies the form of the system of equations:
               = 'N':  A * X = B     (No transpose)
               = 'T':  A**T * X = B  (Transpose)
               = 'C':  A**H * X = B  (Conjugate transpose)

     N         (input) INTEGER
               The order of the 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.

     DL        (input) COMPLEX*16 array, dimension (N-1)
               The (n-1) multipliers that  define  the  matrix  L
               from the LU factorization of A.

     D         (input) COMPLEX*16 array, dimension (N)
               The n diagonal elements of  the  upper  triangular
               matrix U from the LU factorization of A.

     DU        (input) COMPLEX*16 array, dimension (N-1)
               The (n-1) elements of the first  superdiagonal  of
               U.

     DU2       (input) COMPLEX*16 array, dimension (N-2)
               The (n-2) elements of the second superdiagonal  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  indi-
               cates a row interchange was not required.

     B         (input/output)   COMPLEX*16    array,    dimension
               (LDB,NRHS)
               On entry, the right hand side matrix B.  On  exit,
               B is overwritten by the solution matrix X.

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

     INFO      (output) INTEGER
               = 0:  successful exit
               < 0:  if INFO = -i, the i-th argument had an ille-
               gal value

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