Mercurial > matrix-functions
comparison matrixcomp/sparsify.m @ 0:8f23314345f4 draft
Create local repository for matrix toolboxes. Step #0 done.
| author | Antonio Pino Robles <data.script93@gmail.com> |
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| date | Wed, 06 May 2015 14:56:53 +0200 |
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| -1:000000000000 | 0:8f23314345f4 |
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| 1 function A = sparsify(A, p) | |
| 2 %SPARSIFY Randomly set matrix elements to zero. | |
| 3 % S = SPARSIFY(A, P) is A with elements randomly set to zero | |
| 4 % (S = S' if A is square and A = A', i.e. symmetry is preserved). | |
| 5 % Each element has probability P of being zeroed. | |
| 6 % Thus on average 100*P percent of the elements of A will be zeroed. | |
| 7 % Default: P = 0.25. | |
| 8 | |
| 9 if nargin < 2, p = 0.25; end | |
| 10 if p<0 | p>1, error('Second parameter must be between 0 and 1 inclusive.'), end | |
| 11 | |
| 12 [m,n] = size(A); | |
| 13 | |
| 14 if ~isequal(A,A') | |
| 15 A = A .* (rand(m,n) > p); % Unsymmetric case | |
| 16 else | |
| 17 A = triu(A,1) .* (rand(m,n) > p); % Preserve symmetry | |
| 18 A = A + A'; | |
| 19 A = A + diag( diag(A) .* (rand(size(n,1)) > p) ); | |
| 20 end |