All combination of certain min size

Hi, I need to compute all possible combination out of 70 assets that include at least 20 of them.

A binary 0/1 index output would be ideal.

Thanks

[the cyclist]

I estimate that there are 2.6e17 ways to do that. What exactly is it that you want?

Answer 1

[Walter Roberson]

Because of the "at least 20 of them", there will be 1180493606926365010344 of them. It would be a lot shorter to calculate the asset combinations that are not included; there are only 98013791046293080 of those.

Answer 2

[Sean de Wolski]

nchoosek(70,20)

Warning: Result may not be exact. Coefficient is greater than 1.000000e+015 and is only accurate to 15 digits > In nchoosek at 64

 ans =

1.6188e+017

So it's going to take a really long time and use most of the computer memory in the world to do this:

http://en.wikipedia.org/wiki/Orders_of_magnitude_(data)

Answer 3

[Tommaso Sanzin]

Roger! I clearly did not calc the exponential magnitude of the problem. I guess looking for any combination of size 20 out of a universe of 70 is still too much... Thanks for the answers!