NAME

       DDTTRSV - solve one of the systems of equations  L * X = B, L**T * X = B, or L**H * X = B,

SYNOPSIS

       SUBROUTINE DDTTRSV( UPLO, TRANS, N, NRHS, DL, D, DU, B, LDB, INFO )

           CHARACTER       UPLO, TRANS

           INTEGER         INFO, LDB, N, NRHS

           DOUBLE          PRECISION B( LDB, * ), D( * ), DL( * ), DU( * )

PURPOSE

       DDTTRSV solves one of the systems of equations
          L * X = B,  L**T * X = B,  or  L**H * X = B,
          U * X = B,  U**T * X = B,  or  U**H * X = B,
       with factors of the tridiagonal matrix A from the LU factorization computed by DDTTRF.

ARGUMENTS

       UPLO    (input) CHARACTER*1
               Specifies whether to solve with L or U.

       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 array, dimension (N-1)
               The (n-1) multipliers that define the matrix L from the LU factorization 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 superdiagonal of U.

       B       (input/output) COMPLEX 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 illegal value