1DPTSV(1)                 LAPACK routine (version 3.2)                 DPTSV(1)
2
3
4

NAME

6       DPTSV  - computes the solution to a real system of linear equations A*X
7       = B, where A is  an  N-by-N  symmetric  positive  definite  tridiagonal
8       matrix, and X and B are N-by-NRHS matrices
9

SYNOPSIS

11       SUBROUTINE DPTSV( N, NRHS, D, E, B, LDB, INFO )
12
13           INTEGER       INFO, LDB, N, NRHS
14
15           DOUBLE        PRECISION B( LDB, * ), D( * ), E( * )
16

PURPOSE

18       DPTSV  computes the solution to a real system of linear equations A*X =
19       B, where A is an N-by-N symmetric positive definite tridiagonal matrix,
20       and X and B are N-by-NRHS matrices.  A is factored as A = L*D*L**T, and
21       the factored form of A is then used to solve the system of equations.
22

ARGUMENTS

24       N       (input) INTEGER
25               The order of the matrix A.  N >= 0.
26
27       NRHS    (input) INTEGER
28               The number of right hand sides, i.e., the number of columns  of
29               the matrix B.  NRHS >= 0.
30
31       D       (input/output) DOUBLE PRECISION array, dimension (N)
32               On  entry, the n diagonal elements of the tridiagonal matrix A.
33               On exit, the n diagonal elements of the diagonal matrix D  from
34               the factorization A = L*D*L**T.
35
36       E       (input/output) DOUBLE PRECISION array, dimension (N-1)
37               On  entry,  the  (n-1)  subdiagonal elements of the tridiagonal
38               matrix A.  On exit, the (n-1) subdiagonal elements of the  unit
39               bidiagonal  factor  L from the L*D*L**T factorization of A.  (E
40               can also be regarded as the superdiagonal of the unit  bidiago‐
41               nal factor U from the U**T*D*U factorization of A.)
42
43       B       (input/output) DOUBLE PRECISION array, dimension (LDB,NRHS)
44               On  entry, the N-by-NRHS right hand side matrix B.  On exit, if
45               INFO = 0, the N-by-NRHS solution matrix X.
46
47       LDB     (input) INTEGER
48               The leading dimension of the array B.  LDB >= max(1,N).
49
50       INFO    (output) INTEGER
51               = 0:  successful exit
52               < 0:  if INFO = -i, the i-th argument had an illegal value
53               > 0:  if INFO = i, the leading minor of order i is not positive
54               definite,  and the solution has not been computed.  The factor‐
55               ization has not been completed unless i = N.
56
57
58
59 LAPACK routine (version 3.2)    November 2008                        DPTSV(1)