1ZGTSV(1)                 LAPACK routine (version 3.1)                 ZGTSV(1)
2
3
4

NAME

6       ZGTSV - the equation   A*X = B,
7

SYNOPSIS

9       SUBROUTINE ZGTSV( N, NRHS, DL, D, DU, B, LDB, INFO )
10
11           INTEGER       INFO, LDB, N, NRHS
12
13           COMPLEX*16    B( LDB, * ), D( * ), DL( * ), DU( * )
14

PURPOSE

16       ZGTSV  solves the equation
17
18       where  A  is an N-by-N tridiagonal matrix, by Gaussian elimination with
19       partial pivoting.
20
21       Note that the equation  A'*X = B  may be solved  by  interchanging  the
22       order of the arguments DU and DL.
23
24

ARGUMENTS

26       N       (input) INTEGER
27               The order of the matrix A.  N >= 0.
28
29       NRHS    (input) INTEGER
30               The  number of right hand sides, i.e., the number of columns of
31               the matrix B.  NRHS >= 0.
32
33       DL      (input/output) COMPLEX*16 array, dimension (N-1)
34               On entry, DL must contain the (n-1) subdiagonal elements of  A.
35               On  exit, DL is overwritten by the (n-2) elements of the second
36               superdiagonal of the upper triangular matrix U from the LU fac‐
37               torization of A, in DL(1), ..., DL(n-2).
38
39       D       (input/output) COMPLEX*16 array, dimension (N)
40               On  entry, D must contain the diagonal elements of A.  On exit,
41               D is overwritten by the n diagonal elements of U.
42
43       DU      (input/output) COMPLEX*16 array, dimension (N-1)
44               On entry, DU must contain the (n-1) superdiagonal  elements  of
45               A.   On  exit,  DU  is overwritten by the (n-1) elements of the
46               first superdiagonal of U.
47
48       B       (input/output) COMPLEX*16 array, dimension (LDB,NRHS)
49               On entry, the N-by-NRHS right hand side matrix B.  On exit,  if
50               INFO = 0, the N-by-NRHS solution matrix X.
51
52       LDB     (input) INTEGER
53               The leading dimension of the array B.  LDB >= max(1,N).
54
55       INFO    (output) INTEGER
56               = 0:  successful exit
57               < 0:  if INFO = -i, the i-th argument had an illegal value
58               > 0:  if INFO = i, U(i,i) is exactly zero, and the solution has
59               not been computed.  The factorization has  not  been  completed
60               unless i = N.
61
62
63
64 LAPACK routine (version 3.1)    November 2006                        ZGTSV(1)