% (1) data setup:
% 4 datasets (i.e., matrices) with 1044 rows and 55 columns:
M1 = rand(1044,55);
M2 = rand(1044,55);
M3 = rand(1044,55);
M4 = rand(1044,55);
% in one of the datasets, a few columns have negative values:
M2(:,[10 12 19 21 29]) = -M2(:,[10 12 19 21 29]);
% (2) delete the columns with negative values from all datasets:
% idx is a vector of logicals, saying whether
% each column in M2 has any negative values:
idx = any(M2 < 0,1);
% delete those columns from all datasets:
M1(:,idx) = [];
M2(:,idx) = [];
M3(:,idx) = [];
M4(:,idx) = [];
