
CGTTRS(l) ) CGTTRS(l)
NAME
CGTTRS  solve one of the systems of equations A * X = B, A**T * X = B, or A**H * X = B,
SYNOPSIS
SUBROUTINE CGTTRS( TRANS, N, NRHS, DL, D, DU, DU2, IPIV, B, LDB, INFO )
CHARACTER TRANS
INTEGER INFO, LDB, N, NRHS
INTEGER IPIV( * )
COMPLEX B( LDB, * ), D( * ), DL( * ), DU( * ), DU2( * )
PURPOSE
CGTTRS 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
TRANS (input) CHARACTER
Specifies the form of the system of equations. = 'N': A * X = B (No trans
pose)
= 'T': A**T * X = B (Transpose)
= 'C': 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 (N1)
The (n1) 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 (N1)
The (n1) elements of the first superdiagonal of U.
DU2 (input) COMPLEX array, dimension (N2)
The (n2) 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 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).
INFO (output) INTEGER
= 0: successful exit
< 0: if INFO = k, the kth argument had an illegal value
LAPACK version 3.0 15 June 2000 CGTTRS(l) 
