1DPOTF2(1)                LAPACK routine (version 3.1)                DPOTF2(1)
2
3
4

NAME

6       DPOTF2  - the Cholesky factorization of a real symmetric positive defi‐
7       nite matrix A
8

SYNOPSIS

10       SUBROUTINE DPOTF2( UPLO, N, A, LDA, INFO )
11
12           CHARACTER      UPLO
13
14           INTEGER        INFO, LDA, N
15
16           DOUBLE         PRECISION A( LDA, * )
17

PURPOSE

19       DPOTF2 computes the Cholesky factorization of a real symmetric positive
20       definite matrix A.
21
22       The factorization has the form
23          A = U' * U ,  if UPLO = 'U', or
24          A = L  * L',  if UPLO = 'L',
25       where U is an upper triangular matrix and L is lower triangular.
26
27       This is the unblocked version of the algorithm, calling Level 2 BLAS.
28
29

ARGUMENTS

31       UPLO    (input) CHARACTER*1
32               Specifies  whether  the  upper  or lower triangular part of the
33               symmetric matrix A is stored.  = 'U':  Upper triangular
34               = 'L':  Lower triangular
35
36       N       (input) INTEGER
37               The order of the matrix A.  N >= 0.
38
39       A       (input/output) DOUBLE PRECISION array, dimension (LDA,N)
40               On entry, the symmetric matrix A.  If UPLO = 'U', the leading n
41               by  n  upper triangular part of A contains the upper triangular
42               part of the matrix A, and the strictly lower triangular part of
43               A  is  not referenced.  If UPLO = 'L', the leading n by n lower
44               triangular part of A contains the lower triangular part of  the
45               matrix  A,  and  the strictly upper triangular part of A is not
46               referenced.
47
48               On exit, if INFO = 0, the factor U or L from the Cholesky  fac‐
49               torization A = U'*U  or A = L*L'.
50
51       LDA     (input) INTEGER
52               The leading dimension of the array A.  LDA >= max(1,N).
53
54       INFO    (output) INTEGER
55               = 0: successful exit
56               < 0: if INFO = -k, the k-th argument had an illegal value
57               >  0: if INFO = k, the leading minor of order k is not positive
58               definite, and the factorization could not be completed.
59
60
61
62 LAPACK routine (version 3.1)    November 2006                       DPOTF2(1)
Impressum