
CGTSV(l) ) CGTSV(l)
NAME
CGTSV  solve the equation A*X = B,
SYNOPSIS
SUBROUTINE CGTSV( N, NRHS, DL, D, DU, B, LDB, INFO )
INTEGER INFO, LDB, N, NRHS
COMPLEX B( LDB, * ), D( * ), DL( * ), DU( * )
PURPOSE
CGTSV solves the equation A*X = B, where A is an NbyN tridiagonal matrix, by Gaussian
elimination with partial pivoting.
Note that the equation A'*X = B may be solved by interchanging the order of the argu
ments DU and DL.
ARGUMENTS
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/output) COMPLEX array, dimension (N1)
On entry, DL must contain the (n1) subdiagonal elements of A. On exit, DL is
overwritten by the (n2) elements of the second superdiagonal of the upper trian
gular matrix U from the LU factorization of A, in DL(1), ..., DL(n2).
D (input/output) COMPLEX array, dimension (N)
On entry, D must contain the diagonal elements of A. On exit, D is overwritten by
the n diagonal elements of U.
DU (input/output) COMPLEX array, dimension (N1)
On entry, DU must contain the (n1) superdiagonal elements of A. On exit, DU is
overwritten by the (n1) elements of the first superdiagonal of U.
B (input/output) COMPLEX array, dimension (LDB,NRHS)
On entry, the NbyNRHS right hand side matrix B. On exit, if INFO = 0, the Nby
NRHS 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 ith argument had an illegal value
> 0: if INFO = i, U(i,i) is exactly zero, and the solution has not been computed.
The factorization has not been completed unless i = N.
LAPACK version 3.0 15 June 2000 CGTSV(l) 
