Thanks for posting the request for clarification.

The function takes two arrayrefs of numbers, listing all the elements from both arrays in order, ranking them, and returning the sum of ranks for each array. For example, suppose we have my @one=(1..10); my @two=(3.14,4.25,5.36,6.47,7.58);. Then the elements, in order, are 1, 2, 3, 3.14, 4, 4.25, 5, 5.36, 6, 6.47, 7, 7.58, 8, 9, 10, so the ranks are:

1, 2, 3, 3.14, 4, 4.25, 5, 5.36, 6,  6.47,  7,  7.58,  8,  9, 10
1, 2, 3, 4   , 5, 6   , 7, 8   , 9, 10   , 11, 12,    13, 14, 15 # ranks

Then @one would have the ranks 1, 2, 3, 5, 7, 9, 11, 13, 14, 15, for a sum of 80, and @two would have the ranks 4, 6, 8, 10, 12, for a sum of 40, so the function could return {one=>80, two=>40}.

(That's not exactly how the module's function works: it takes a hashref as an argument, and… whatever. But the point is that it needs to "know about" two arrays and return a number for each.)

It gets more complicated when there are multiple copies of the same number. If @one=(1..5); @two=(3,3.14,4,4); then the ranking is

1, 2, 3  , 3  , 3.14, 4, 4, 4, 5
1, 2, 3.5, 3.5, 5   , 7, 7, 7, 9 # ranks

because each element is given the arithmetic mean (average) of the possible ranks it qualifies for (the mean of 6, 7, and 8 is 7; the mean of 3 and 4 is 3.5).