what functions should I look at to achieve [triples] as i need it 5*3 where number of AP is not repeated

What functions should I look at to achieve [triples] as I need it 5*3 where number of AP is not repeated

clc;
clear all
close all
% --------------------------------------------------------
% user = PPP
% BS = PPP 
% **********************************************************************
% Step 1) User deployment:
area = 100*100e-6;
user_intensity = 600;                  % number of users that you want
center = [50e-3 ,50e-3];                  % center coordinates of the circle 
radius =50e-3 ;                        % radius of the circle
%% nusers = poissrnd(user_intensity*area);        % random angle
nusers = 60;
r = 2*radius*rand(nusers,2);
Ux = r(:, 1);                      % x-coordinates of users
Uy = r(:, 2);                      % y-coordinates of users
intensity_of_BS = 1000;                   % lambda of the PPP
%% npoints = poissrnd(area*intensity_of_BS);    % create a PPP 
npoints=15;
pproc = 2*radius*rand(npoints,2);
BSx = pproc(:, 1);                      % x-coordinates of base stations
BSy = pproc(:, 2);                      % y-coordinates of base stations

%% calculating distance Between BS (Update)
points= [BSx BSy];
for xIndex = 1 : length(BSx)
  for yIndex = 1 : length(BSy)
    distances(xIndex, yIndex) = sqrt((BSx(xIndex)-BSx(yIndex))^2 + (BSy(xIndex)-BSy(yIndex))^2);
  end
end
[distances, I] = sort(distances,'descend');
%%Group
td = distances;
tripidx = 0;
triples = [];
std = size(td);
while nnz(td(:) ~= 0 & ~isnan(td(:))) >= 2
  [~, maxidx] = max(td(:));
  [maxr, maxc] = ind2sub(std, maxidx);
  td(maxr, maxc) = nan;
  [~, maxc2] = max(td(maxr, :));
  tripidx = tripidx + 1;
  triples(tripidx, :) = [maxr, maxc, maxc2];
  td([maxr maxc maxc2], :) = nan;
  td(:, [maxr maxc maxc2]) = nan;
end