Peter Kupfer wrote:
That function is =combine(num;num)
I'm being stupid. I can't get this to work.
I am using OOo Calc m87. I put this in the cell: =combine(3;2)
But I get a 'name' error: #NAME?
:-(
Sorry should be combin, not combine (-e).
Just to check myself, nCr is when you select from a group but can only pick each thing once, like Bingo.
nPr is when you can pick out of a group but you pick things multiple times. Like if I had a set {1,2,3} and I was going to pick three things, I could pick {3,3,3}. Right?
In both nPr and nCr you are picking items that are different. With permutations (nPr) order is significant. So "123" is not the same as "321". In combinations order doesn't matter. So, combinations are like Bingo, and permutations are like standing on a line at the ATM :-)
But in any event, what you suggested is probably what the 'combinea' function is supposed to do (if I could just get it to work).
Let's see... let's try using combinea(3;2). If your theory is correct, then the combinations-with-repetitions would be: 11, 12, 13, 22, 23, 33. So the answer should be 6. Is that what you get?
For illustration, for combine(3;2) the combinations would be: 12, 13, 23. So the answer should be 3.
If your theory is correct I would expect:
combinea(a;b) == combine(a;b) + a
Does that match what you see?
Your theory falls apart when b doesn't = 2.
=combina(5;4) = 70 =combin(5;4) = 5
If you have time, play more. If combina=nPr, how are they different? (According to my good ole TI-89, they are not the same thing.)
Thanks,
Cheers,
-- Peter Kupfer OOo user since 'OO4 http://peschtra.tripod.com/open_office/ooo_front.htm
