As you mentioned that the matrix having size 146652x1, which means it has 1 column. Prefer logical conditional statement.
idx=mat_data>1;
It's return logical data 1, where the value greater than 1, else 0.
Or
If you mat data having multiple columns and rows, force all elements greater than 2 to be Zero
results=mat_data>1 & mat_data
Or
If you wish to check individual cloumn data
for i=1:coumn_num
if mat_data(:,i)>1
% Do
end
end
