www.gusucode.com > 矩阵计算工具箱 - mctoolbox源码程序 > matrixcomp\sparsify.m
function A = sparsify(A, p) %SPARSIFY Randomly set matrix elements to zero. % S = SPARSIFY(A, P) is A with elements randomly set to zero % (S = S' if A is square and A = A', i.e. symmetry is preserved). % Each element has probability P of being zeroed. % Thus on average 100*P percent of the elements of A will be zeroed. % Default: P = 0.25. if nargin < 2, p = 0.25; end if p<0 | p>1, error('Second parameter must be between 0 and 1 inclusive.'), end [m,n] = size(A); if ~isequal(A,A') A = A .* (rand(m,n) > p); % Unsymmetric case else A = triu(A,1) .* (rand(m,n) > p); % Preserve symmetry A = A + A'; A = A + diag( diag(A) .* (rand(size(n,1)) > p) ); end