Why does the sum of the counts delivered by hist2 not equal the number of rows in x and y?

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Charles Gallistel 2019-12-11

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https://ww2.mathworks.cn/matlabcentral/answers/496210-why-does-the-sum-of-the-counts-delivered-by-hist2-not-equal-the-number-of-rows-in-x-and-y

评论： Charles Gallistel 2019-12-12

Here is the documentation Example for hist2:

events = 1000000;
  x1 = sqrt(0.05)*randn(events,1)-0.5; x2 = sqrt(0.05)*randn(events,1)+0.5;
  y1 = sqrt(0.05)*randn(events,1)+0.5; y2 = sqrt(0.05)*randn(events,1)-0.5;
  x= [x1;x2]; y = [y1;y2];

For linearly spaced edges:

  xedges = linspace(-1,1,64); yedges = linspace(-1,1,64);
  histmat = hist2(x, y, xedges, yedges);

When I run the 6 lines of code above (not including the 'For...), I get a matrix in which the total number of counts is substantially less than the lengths of x & y (2000000)

sum(histmat(1:end))

ans =

1949700.00

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Charles Gallistel 2019-12-12

I did not realize that it was not a part of MATLAB. I have just looked at the code for the one I am using and it gives no version information, nor copyright, etc. I will try others.

Charles Gallistel 2019-12-12