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comparison scripts/sparse/sprand.m @ 6498:2c85044aa63f

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[project @ 2007-04-05 17:59:47 by jwe]
author jwe
date Thu, 05 Apr 2007 17:59:47 +0000
parents 34f96dd5441b
children 93c65f2a5668
comparison
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6497:fc8ed0c77e08 6498:2c85044aa63f
28 ## at the price of sometimes lower density than desired 28 ## at the price of sometimes lower density than desired
29 ## David Bateman 29 ## David Bateman
30 ## 2004-10-20 Texinfo help and copyright message 30 ## 2004-10-20 Texinfo help and copyright message
31 31
32 function S = sprand (m, n, d) 32 function S = sprand (m, n, d)
33 if nargin == 1 33 if (nargin == 1)
34 [i,j,v,nr,nc] = spfind(m); 34 [i, j, v, nr, nc] = spfind (m);
35 S = sparse (i,j,rand(size(v)),nr,nc); 35 S = sparse (i, j, rand (size (v)), nr, nc);
36 elseif nargin == 3 36 elseif (nargin == 3)
37 mn = n*m; 37 mn = n*m;
38 k = round(d*mn); # how many entries in S would be satisfactory? 38 ## how many entries in S would be satisfactory?
39 idx=unique(fix(rand(min(k*1.01,k+10),1)*mn))+1; 39 k = round (d*mn);
40 # idx contains random numbers in [1,mn] 40 idx = unique (fix (rand (min (k*1.01, k+10), 1) * mn)) + 1;
41 # generate 1% or 10 more random values than necessary 41 ## idx contains random numbers in [1,mn]
42 # in order to reduce the probability that there are less than k 42 ## generate 1% or 10 more random values than necessary in order to
43 # distinct values; 43 ## reduce the probability that there are less than k distinct
44 # maybe a better strategy could be used 44 ## values; maybe a better strategy could be used but I don't think
45 # but I don't think it's worth the price 45 ## it's worth the price
46 k = min(length(idx),k); # actual number of entries in S 46
47 j = floor((idx(1:k)-1)/m); 47 ## actual number of entries in S
48 k = min (length (idx), k);
49 j = floor ((idx(1:k)-1)/m);
48 i = idx(1:k) - j*m; 50 i = idx(1:k) - j*m;
49 if isempty(i) 51 if (isempty (i))
50 S = sparse(m,n); 52 S = sparse (m, n);
51 else 53 else
52 S = sparse(i,j+1,rand(k,1),m,n); 54 S = sparse (i, j+1, rand (k, 1), m, n);
53 endif 55 endif
54 else 56 else
55 print_usage (); 57 print_usage ();
56 endif 58 endif
57 endfunction 59 endfunction