1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
|
function sqr_example
%SQR_EXAMPLE test cs_sqr
% Example:
% sqr_example
% See also: testall
% CXSparse, Copyright (c) 2006-2022, Timothy A. Davis. All Rights Reserved.
% SPDX-License-Identifier: LGPL-2.1+
Prob = ssget (706) ;
A = Prob.A' ;
q = colamd (A) ;
A = A (:,q) ;
A = sprandn (A) ;
[m n] = size (A) ;
[vnz, rnz, parent, c, leftmost, p] = cs_sqr(A) ;
m2 = length (p) ;
B = [A ; sparse(m2-m,n)] ;
B = B (p,q) ;
R1 = gqr3 (B) ;
clf
subplot (2,2,1) ; spy(A)
subplot (2,2,3) ; spy (chol (A'*A + 100*speye(n))) ;
subplot (2,2,4) ; spy (R1) ;
|
