1DGTTS2(1)           LAPACK auxiliary routine (version 3.1)           DGTTS2(1)
2
3
4

NAME

6       DGTTS2 - one of the systems of equations  A*X = B or A'*X = B,
7

SYNOPSIS

9       SUBROUTINE DGTTS2( ITRANS, N, NRHS, DL, D, DU, DU2, IPIV, B, LDB )
10
11           INTEGER        ITRANS, LDB, N, NRHS
12
13           INTEGER        IPIV( * )
14
15           DOUBLE         PRECISION  B(  LDB,  *  ), D( * ), DL( * ), DU( * ),
16                          DU2( * )
17

PURPOSE

19       DGTTS2 solves one of the systems of equations
20          A*X = B  or  A'*X = B, with a tridiagonal matrix A using the LU fac‐
21       torization computed by DGTTRF.
22
23

ARGUMENTS

25       ITRANS  (input) INTEGER
26               Specifies the form of the system of equations.  = 0:  A * X = B
27               (No transpose)
28               = 1:  A'* X = B  (Transpose)
29               = 2:  A'* X = B  (Conjugate transpose = Transpose)
30
31       N       (input) INTEGER
32               The order of the matrix A.
33
34       NRHS    (input) INTEGER
35               The number of right hand sides, i.e., the number of columns  of
36               the matrix B.  NRHS >= 0.
37
38       DL      (input) DOUBLE PRECISION array, dimension (N-1)
39               The (n-1) multipliers that define the matrix L from the LU fac‐
40               torization of A.
41
42       D       (input) DOUBLE PRECISION array, dimension (N)
43               The n diagonal elements of the upper triangular matrix  U  from
44               the LU factorization of A.
45
46       DU      (input) DOUBLE PRECISION array, dimension (N-1)
47               The (n-1) elements of the first super-diagonal of U.
48
49       DU2     (input) DOUBLE PRECISION array, dimension (N-2)
50               The (n-2) elements of the second super-diagonal of U.
51
52       IPIV    (input) INTEGER array, dimension (N)
53               The  pivot  indices;  for  1 <= i <= n, row i of the matrix was
54               interchanged with row IPIV(i).  IPIV(i) will always be either i
55               or  i+1;  IPIV(i)  =  i  indicates  a  row  interchange was not
56               required.
57
58       B       (input/output) DOUBLE PRECISION array, dimension (LDB,NRHS)
59               On entry, the matrix of right hand side vectors B.  On exit,  B
60               is overwritten by the solution vectors X.
61
62       LDB     (input) INTEGER
63               The leading dimension of the array B.  LDB >= max(1,N).
64
65
66
67 LAPACK auxiliary routine (versionNo3v.e1m)ber 2006                       DGTTS2(1)
Impressum