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Diffstat (limited to 'sourcecodes/bnt-master/KPMtools/nchoose2.m')
| -rw-r--r-- | sourcecodes/bnt-master/KPMtools/nchoose2.m | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/sourcecodes/bnt-master/KPMtools/nchoose2.m b/sourcecodes/bnt-master/KPMtools/nchoose2.m new file mode 100644 index 00000000..1827d053 --- /dev/null +++ b/sourcecodes/bnt-master/KPMtools/nchoose2.m @@ -0,0 +1,35 @@ +function c = nchoose2(v, f) +%NCHOOSE2 All combinations of N elements taken two at a time. +% +% NCHOOSE2(1:N) or NCHOOSEK(V) where V is a vector of length N, +% produces a matrix with N*(N-1)/2 rows and K columns. Each row of +% the result has K of the elements in the vector V. +% +% NCHOOSE2(N,FLAG) is the same as NCHOOSE2(1:N) but faster. +% +% NCHOOSE2(V) is much faster than NCHOOSEK(V,2). +% +% See also NCHOOSEK, PERMS. + +% Author: Peter J. Acklam +% Time-stamp: 2000-03-03 13:03:59 +% E-mail: jacklam@math.uio.no +% URL: http://www.math.uio.no/~jacklam + + nargs = nargin; + if nargs < 1 + error('Not enough input arguments.'); + elseif nargs == 1 + v = v(:); + n = length(v); + elseif nargs == 2 + n = v; + else + error('Too many input arguments.'); + end + + [ c(:,2), c(:,1) ] = find( tril( ones(n), -1 ) ); + + if nargs == 1 + c = v(c); + end |
