How to transform a file composed on several vectors, transforming non-negative values of a certain column into "0" for those corresponding data?

Hello,
I am trying to transform a file (tmp.asc) made of three vectors based
on the data of the 2nd column

13 20 3
65 -16 9
43 -10 8
10 -5 2
5 10 0
0 0 0

I want to create a new file only containing negative values from column
2, the rest would become 0:

0 0 0
65 -16 9
43 -10 8
10 -5 2
0 0 0
0 0 0

Similarly for positive values from colum 2, the rest would become 0:

13 20 3
0 0 0
0 0 0
0 0 0
5 10 0
0 0 0


How would I do the following?
I know how to do the following:

%For values of column 2 <0
m=find(tmp(:,2)<0);
nf=[tmp(m,1) tmp(m,2) tmp(m,3)]

---output would be:
65 -16 9
43 -10 8
10 -5 2

%this would only save the data with Column 2 values <0
What should I do to also include other value of Column 2 greater and
equal to 0 to have this?
0 0 0
65 -16 9
43 -10 8
10 -5 2
0 0 0
0 0 0



Thank you.

.