freezing is the name of the function. So when you write freezing inside the function, you're telling it to call itself. Of course, once it's called itself, it reexecute that freezing call ad finitum. Hence the infinite recursion.
You probably meant to use the input variable temperatures inside that function
function numfreeze = freeezing(temperatures)
numfreeze = numel(temperatures(temperatures<32))
end
While the above will work, it's not the most efficient. You're deleting all the elements above 32 to then find out how many remain. It be simpler to just count how many true values are in your logical array and not bother with the deletion, so:
function numfreeze = freeezing(temperatures)
numfreeze = nnz(temperatures<32); %you can also use sum instead of nnz
end
