How to apply for loop?

I have a signal of 100*1 size and I have applied the below commands on the signal.Now if I have 100*3 size and I need to apply the same commands for each column seperately with the help of for loop .How can I use for loop here .If My signal is X=round(randn(100,3),0).Then How can i apply the commands for each column

X=round(randn(100,1),0);
[locx ~]=find(X>0);
mg_f(locx)=X(locx);
[locx ~]=find(X<0);
mg_f(locx)=-X(locx);
mg_r=mg_f';

Answer 1

[David Hill]

for k=1:3
    X(:,k)=X(:,k)+%whatever you are doing to the column
end