Get all the combinations of descendent state pairs, in 0-based index form

Description

Given the number of states, this function returns all of the pairs of indexes corresponding to those states.

Usage

1
2
  Rcpp_combn_zerostart(n_to_choose_from, k_to_choose,
    maxlim = 1e+07)

Arguments

n_to_choose_from

N in N choose K

k_to_choose

K in N choose K

maxlim

To avoid memory overruns, the number of combinations can be no larger than maxlim (default: 1e+07)

Details

The C++ version is MUCH faster than the plain-R version.

Value

outarray an integer matrix with outarray rows; the number of columns is the number of combinations.

Author(s)

Nicholas Matzke matzke@berkeley.edu

References

Matzke N (2012). "Founder-event speciation in BioGeoBEARS package dramatically improves likelihoods and alters parameter inference in Dispersal-Extinction-Cladogenesis (DEC) analyses." _Frontiers of Biogeography_, *4*(suppl. 1), pp. 210. ISSN 1948-6596, Poster abstract published in the Conference Program and Abstracts of the International Biogeography Society 6th Biannual Meeting, Miami, Florida. Poster Session P10: Historical and Paleo-Biogeography. Poster 129B. January 11, 2013, <URL: http://phylo.wikidot.com/matzke-2013-international-biogeography-society-poster>.

See Also

rcpp_calc_anclikes_sp, rcpp_mult2probvect, rcpp_convolve

Examples

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Rcpp_combn_zerostart(n_to_choose_from=4, k_to_choose=2, maxlim=1e+07)
Rcpp_combn_zerostart(n_to_choose_from=4, k_to_choose=3, maxlim=1e+07)

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