I want to count the rows if the value of the column, from bottom up,
changes sign (from positive to negative or vise versa.). As soon as
the sign is changed or the number is the value of a zero, counter
finishes counter.

For example,

-2.1 31.2 -2.1
0.3 44.8 1.6
-1.1 -9.4 5.3
44 10.4 9
13.1 -2.2 0
12.2 -11.1 3.2
counter = 3 counter = 2 counter = 1

Thanks.