comparison examples/private/spdiag.m @ 1:7750624e0c73 version0.5

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author idamnjanovic
date Thu, 05 Nov 2009 16:36:01 +0000
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0:5181bee80bc1 1:7750624e0c73
1 function Y = spdiag(V,K)
2 %SPDIAG Sparse diagonal matrices.
3 % SPDIAG(V,K) when V is a vector with N components is a sparse square
4 % matrix of order N+ABS(K) with the elements of V on the K-th diagonal.
5 % K = 0 is the main diagonal, K > 0 is above the main diagonal and K < 0
6 % is below the main diagonal.
7 %
8 % SPDIAG(V) is the same as SPDIAG(V,0) and puts V on the main diagonal.
9 %
10 % See also DIAG, SPDIAGS.
11
12
13 % Ron Rubinstein
14 % Computer Science Department
15 % Technion, Haifa 32000 Israel
16 % ronrubin@cs
17 %
18 % June 2008
19
20
21 if (nargin<2)
22 K = 0;
23 end
24
25 n = length(V) + abs(K);
26
27 if (K>0)
28 i = 1:length(V);
29 j = K+1:n;
30 elseif (K<0)
31 i = -K+1:n;
32 j = 1:length(V);
33 else
34 i = 1:n;
35 j = 1:n;
36 end
37
38 Y = sparse(i,j,V(:),n,n);