1DPTTS2(1)                LAPACK routine (version 3.1)                DPTTS2(1)
2
3
4

NAME

6       DPTTS2  -  a tridiagonal system of the form  A * X = B using the L*D*L'
7       factorization of A computed by DPTTRF
8

SYNOPSIS

10       SUBROUTINE DPTTS2( N, NRHS, D, E, B, LDB )
11
12           INTEGER        LDB, N, NRHS
13
14           DOUBLE         PRECISION B( LDB, * ), D( * ), E( * )
15

PURPOSE

17       DPTTS2 solves a tridiagonal system of the form
18          A * X = B using the L*D*L' factorization of A computed by DPTTRF.  D
19       is  a diagonal matrix specified in the vector D, L is a unit bidiagonal
20       matrix whose subdiagonal is specified in the vector E, and X and B  are
21       N by NRHS matrices.
22
23

ARGUMENTS

25       N       (input) INTEGER
26               The order of the tridiagonal matrix A.  N >= 0.
27
28       NRHS    (input) INTEGER
29               The  number of right hand sides, i.e., the number of columns of
30               the matrix B.  NRHS >= 0.
31
32       D       (input) DOUBLE PRECISION array, dimension (N)
33               The n diagonal elements of  the  diagonal  matrix  D  from  the
34               L*D*L' factorization of A.
35
36       E       (input) DOUBLE PRECISION array, dimension (N-1)
37               The  (n-1) subdiagonal elements of the unit bidiagonal factor L
38               from the L*D*L' factorization of A.  E can also be regarded  as
39               the superdiagonal of the unit bidiagonal factor U from the fac‐
40               torization A = U'*D*U.
41
42       B       (input/output) DOUBLE PRECISION array, dimension (LDB,NRHS)
43               On entry, the right hand side vectors B for the system of  lin‐
44               ear equations.  On exit, the solution vectors, X.
45
46       LDB     (input) INTEGER
47               The leading dimension of the array B.  LDB >= max(1,N).
48
49
50
51 LAPACK routine (version 3.1)    November 2006                       DPTTS2(1)