is it possible to set up a loop to obtain the expected minimum value of a set of comparisons?

[Angel Valls]

Hello! I'm trying to set a loop to obtain the minimum expected value of various comparisons, so far I have managed to obtain the minimum value of a variable using the following code:

mata
o = st_matrix("o")
fr= (rowsum(o)* colsum(o)) / sum(o)
minfr= min(fr)
st_matrix("minfr", minfr)
end

when I try to set the loop to obtain the different minimal expected values changing fr for `c' the error r(1) pops up....
Is it possible to set a loop to obtain the minimum value of n comparisons?