How can i save the time for calculating a combination (nchossek(1:10000,2)) ?thank you

How can i save the time for calculating a combination (nchoosek(1:10000,2)) ?thank you

[Guillaume]

That's around 5e9 (5000 million!) different combinations! No matter what you do, it's going to take a while to compute.

[Matt J]

And will require 40GB to store, assuming single floating point.

[pengcheng]

if i want to calculer nchoosek(1:10000,2),do you have some advices to accelerate the calculation?

[Guillaume]

It's still 49e6 (49 million) combinations. You may want to rethink what you are doing (or be prepared to wait).

Note to check how many combinations that is:

nchoosek(10000, 2) %this value on the other is very fast to calculate

[pengcheng]

yes,i agree with you，that has a great combination,but these combinations are what i need,do you know other software or Parallel Computing Toolbox，like thses,can help me save time? thank you

[José-Luis]

I would encourage you to re-think your approach. You might want all combinations, but you probably don't need to store all of them. If so, it becomes an indexing problem.