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Re: Obtaining terms in an expansionby ivancho (Hermit) 
on Jan 06, 2006 at 00:57 UTC ( #521394=note: print w/replies, xml )  Need Help?? 
ok, so the 2^N terms are each a product of N terms, a[i][j], where j can be 0 or 1 and i goes from 0 to N1 ie, each one looks like, say a[0][0] * a[1][0] * a[2][1] * a[3][0] * ... * a[N1][1] So, we want do some binary magic. how about something like:
note, $size must be a power of 2, for vec to work, and unless you're on a 64bit machine, it probably cannot be more than 32. also, this works for $N no more than 31(32?)  but you may have other problems (memory say), if you want to go above that. Hope this helps.
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