function plotcounthist(spikes, w)
% Plot histogram of spike counts.
%
% Arguments:
%   spikes: a cell array of vectors of spike times in seconds
%   w: duration of window in seconds for computing the counts
    n = counts(spikes, w);
    maxn = max(n);
    [counts, bins] = hist(n, 0:1:maxn+10);
    counts = counts / sum(counts);
    bar(bins, counts);
    xlabel('counts k');
    ylabel('P(k)');
end