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comparison spdiagsVariablePeriodic.m @ 756:f891758ad7a4 feature/d1_staggered

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Merge with feature/utux2d.
author Martin Almquist <malmquist@stanford.edu>
date Sat, 16 Jun 2018 14:30:45 -0700
parents 50e77b15d841
children 8c65ef13df89
comparison
equal deleted inserted replaced
755:14f0058356f2 756:f891758ad7a4
1 function A = spdiagsVariablePeriodic(vals,diags)
2 % Creates an m x m periodic discretization matrix.
3 % vals - m x ndiags matrix of values
4 % diags - 1 x ndiags vector of the 'center diagonals' that vals end up on
5 % vals that are not on main diagonal are going to spill over to
6 % off-diagonal corners.
7
8 default_arg('diags',0);
9
10 [m, ~] = size(vals);
11
12 A = sparse(m,m);
13
14 for i = 1:length(diags)
15
16 d = diags(i);
17 a = vals(:,i);
18
19 % Sub-diagonals
20 if d < 0
21 a_bulk = a(1+abs(d):end);
22 a_corner = a(1:1+abs(d)-1);
23 corner_diag = m-abs(d);
24 A = A + spdiagVariable(a_bulk, d);
25 A = A + spdiagVariable(a_corner, corner_diag);
26
27 % Super-diagonals
28 elseif d > 0
29 a_bulk = a(1:end-d);
30 a_corner = a(end-d+1:end);
31 corner_diag = -m + d;
32 A = A + spdiagVariable(a_bulk, d);
33 A = A + spdiagVariable(a_corner, corner_diag);
34
35 % Main diagonal
36 else
37 A = A + spdiagVariable(a, 0);
38 end
39
40 end
41
42 end