HIST function with negative center and single event.

Dear all,

My program runs into issue with 'hist' when certain criteria meet. Following is the code:

tr_min_center = floor(min(spike_times)/bin_size)*bin_size + (.5*bin_size);

tr_max_center = ceil(max(spike_times)/bin_size)*bin_size - (.5*bin_size);

tr_centers = tr_min_center:bin_size:tr_max_center;

[tr_n, tr_xout] = hist(spike_times, tr_centers);

When there is only one event in spike_time with a negative number (relate to a synchronization time point), so there is only one negative center, function 'hist' give out error like: Attempted to access xx(0); index must be a positive integer or logical.

I track it down in 'hist' at code line 67 to 75:

if length(x) == 1

           if miny == maxy,
            miny = miny - floor(x/2) - 0.5; 
            maxy = maxy + ceil(x/2) - 0.5;
           end
          binwidth = (maxy - miny) ./ x;
          xx = miny + binwidth*(0:x);  -- This is the line error occurred since x is a negative number.

Could someone help provide a fix. Thank you!

Answer 1

[Jan]

As the documentation of HIST explains, "HIST(Y, M)" uses M bins, if M is a scalar. Using a negative or not integer number of bins must fail.

Check the number of bins before calling HIST: For a single bin the calculations are very cheap.

[Yonghe]

Thank you! Your suggestion works.