1CPOSV(1)              LAPACK driver routine (version 3.2)             CPOSV(1)
2
3
4

NAME

6       CPOSV  -  computes the solution to a complex system of linear equations
7       A * X = B,
8

SYNOPSIS

10       SUBROUTINE CPOSV( UPLO, N, NRHS, A, LDA, B, LDB, INFO )
11
12           CHARACTER     UPLO
13
14           INTEGER       INFO, LDA, LDB, N, NRHS
15
16           COMPLEX       A( LDA, * ), B( LDB, * )
17

PURPOSE

19       CPOSV computes the solution to a complex system of linear equations
20          A * X = B, where A is an N-by-N Hermitian positive  definite  matrix
21       and X and B are N-by-NRHS matrices.
22       The Cholesky decomposition is used to factor A as
23          A = U**H* U,  if UPLO = 'U', or
24          A = L * L**H,  if UPLO = 'L',
25       where  U  is  an  upper  triangular matrix and  L is a lower triangular
26       matrix.  The factored form of A is then used to  solve  the  system  of
27       equations A * X = B.
28

ARGUMENTS

30       UPLO    (input) CHARACTER*1
31               = 'U':  Upper triangle of A is stored;
32               = 'L':  Lower triangle of A is stored.
33
34       N       (input) INTEGER
35               The  number  of linear equations, i.e., the order of the matrix
36               A.  N >= 0.
37
38       NRHS    (input) INTEGER
39               The number of right hand sides, i.e., the number of columns  of
40               the matrix B.  NRHS >= 0.
41
42       A       (input/output) COMPLEX array, dimension (LDA,N)
43               On  entry,  the Hermitian matrix A.  If UPLO = 'U', the leading
44               N-by-N upper triangular part of A contains the upper triangular
45               part of the matrix A, and the strictly lower triangular part of
46               A is not referenced.  If UPLO = 'L', the leading  N-by-N  lower
47               triangular  part of A contains the lower triangular part of the
48               matrix A, and the strictly upper triangular part of  A  is  not
49               referenced.   On  exit, if INFO = 0, the factor U or L from the
50               Cholesky factorization A = U**H*U or A = L*L**H.
51
52       LDA     (input) INTEGER
53               The leading dimension of the array A.  LDA >= max(1,N).
54
55       B       (input/output) COMPLEX array, dimension (LDB,NRHS)
56               On entry, the N-by-NRHS right hand side matrix B.  On exit,  if
57               INFO = 0, the N-by-NRHS solution matrix X.
58
59       LDB     (input) INTEGER
60               The leading dimension of the array B.  LDB >= max(1,N).
61
62       INFO    (output) INTEGER
63               = 0:  successful exit
64               < 0:  if INFO = -i, the i-th argument had an illegal value
65               >  0:   if  INFO  = i, the leading minor of order i of A is not
66               positive definite, so the factorization could not be completed,
67               and the solution has not been computed.
68
69
70
71 LAPACK driver routine (version 3.N2o)vember 2008                        CPOSV(1)
Impressum