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

NAME

6       SGBTRS  -  a system of linear equations  A * X = B or A' * X = B with a
7       general band matrix A using the LU factorization computed by SGBTRF
8

SYNOPSIS

10       SUBROUTINE SGBTRS( TRANS, N, KL, KU, NRHS, AB, LDAB, IPIV, B, LDB, INFO
11                          )
12
13           CHARACTER      TRANS
14
15           INTEGER        INFO, KL, KU, LDAB, LDB, N, NRHS
16
17           INTEGER        IPIV( * )
18
19           REAL           AB( LDAB, * ), B( LDB, * )
20

PURPOSE

22       SGBTRS solves a system of linear equations
23          A  * X = B  or  A' * X = B with a general band matrix A using the LU
24       factorization computed by SGBTRF.
25
26

ARGUMENTS

28       TRANS   (input) CHARACTER*1
29               Specifies the form of the system of equations.  = 'N':  A * X =
30               B  (No transpose)
31               = 'T':  A'* X = B  (Transpose)
32               = 'C':  A'* X = B  (Conjugate transpose = Transpose)
33
34       N       (input) INTEGER
35               The order of the matrix A.  N >= 0.
36
37       KL      (input) INTEGER
38               The number of subdiagonals within the band of A.  KL >= 0.
39
40       KU      (input) INTEGER
41               The number of superdiagonals within the band of A.  KU >= 0.
42
43       NRHS    (input) INTEGER
44               The  number of right hand sides, i.e., the number of columns of
45               the matrix B.  NRHS >= 0.
46
47       AB      (input) REAL array, dimension (LDAB,N)
48               Details of the LU factorization of the band matrix A,  as  com‐
49               puted  by  SGBTRF.   U  is  stored  as an upper triangular band
50               matrix with KL+KU superdiagonals in rows 1 to KL+KU+1, and  the
51               multipliers  used  during  the factorization are stored in rows
52               KL+KU+2 to 2*KL+KU+1.
53
54       LDAB    (input) INTEGER
55               The leading dimension of the array AB.  LDAB >= 2*KL+KU+1.
56
57       IPIV    (input) INTEGER array, dimension (N)
58               The pivot indices; for 1 <= i <= N, row i  of  the  matrix  was
59               interchanged with row IPIV(i).
60
61       B       (input/output) REAL array, dimension (LDB,NRHS)
62               On  entry, the right hand side matrix B.  On exit, the solution
63               matrix X.
64
65       LDB     (input) INTEGER
66               The leading dimension of the array B.  LDB >= max(1,N).
67
68       INFO    (output) INTEGER
69               = 0:  successful exit
70               < 0: if INFO = -i, the i-th argument had an illegal value
71
72
73
74 LAPACK routine (version 3.1)    November 2006                       SGBTRS(1)
Impressum