NrParts: Find the number of partitions for a given total Q and number of parts N.
Description
This function was recoded and modified from GAP source
code: www.gap-system.org. Modifications for speed were
based on the proposition that the number of partitions of
Q having N parts is equal to the number of partitions of
Q having N parts is equal to the number of partitions of
Q - N, if N > Q/2 (for odd Q) or if N >= Q/2 (for even Q)
Usage
NrParts(Q, N = NULL, use_c = TRUE)
Arguments
Q
Total sum
N
Number of items to sum across, if not specified
than all possible values are considered
use_c
logical, defaults to TRUE, the number of
partitions is computed in c