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| xt_n_choose_k(3) | FreeBSD Library Functions Manual | xt_n_choose_k(3) |
LIBRARY
#include <xtend/math.h> -lxtend
SYNOPSIS
#include <stdint.h> #include "math.h" unsigned long xt_n_choose_k(unsigned long n, unsigned long k)
ARGUMENTS
n Number of items to choose from k Number of items chosen
DESCRIPTION
Compute the binomial coefficient N choose K = N! / (K! * (N-K)!). This represents the number of ways to choose K items out of a pool of N, such that we don't care about order. E.g., if choosing 2 letters from the set [A B C D E], [C D] is considered the same [D C].This implementation avoids overflow by alternating multiply and divide operations (rather than try to compute factorials first, which will fail for relatively small values of N or K).
RETURN VALUES
The number of ways to choose K items from N objects.EXAMPLES
#include <xtend/math.h>
unsigned long n = 5, k = 2;
printf("Ways to choose %lu items from %lu = %lun",
k, n, xt_binomial(n, k));
SEE ALSO
lgamma(3)
Visit the GSP FreeBSD Man Page Interface.
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