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Expected input number 2, edges, to be one of these types

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SugerCodeCude
SugerCodeCude on 1 Feb 2021
Commented: dpb on 3 Feb 2021
Hello all,
Here I am doing a Chi-Square calculation
main
data = randi([0,10],1,20);
% dummy variable
% 10, 0.05, 'unif', 1.5, 2.9
n = 10;
alpha = 0.05;
dist = 'unif';
a1 = 1.5;
a2 = 2.9;
a3 = 3.0;
%Call to the function
[chi2, critical] = chi2test (data, n, alpha, dist, a1, a2);
The function is straigth forward, however the part I am have a issue is the prod, and the invcdf anonymous function. I do not have the tool kit for the cdf, so I did it by sprintf, using the histcounts. Here is where the issue lays, is there a way to get around this error?
function [chi2, critical] = chi2test (data, n, alpha, dist, a1, a2)
prob = @(a,b) sprintf('cdf(''%s'', b, %10.10g, %10.10g) - cdf(''%s'', a, %10.10g, %10.10g)', dist, a1, a2, dist, a1, a2);
invcdf = @(x) sprintf('icdf(''%s'', x, %10.10g, %10.10g)', dist, a1, a2);
pi = (1/n) .* (0:n);
intvls = invcdf(pi);
% The error is thrown here
o_freq = histcounts(data, intvls);
end
I recevie the following error
Error using histcounts
Expected input number 2, edges, to be one of these types:
double, single, uint8, uint16, uint32, uint64, int8, int16, int32, int64, logical
Thank you all for any help

Accepted Answer

Steven Lord
Steven Lord on 1 Feb 2021
function [chi2, critical] = chi2test (data, n, alpha, dist, a1, a2)
prob = @(a,b) sprintf('cdf(''%s'', b, %10.10g, %10.10g) - cdf(''%s'', a, %10.10g, %10.10g)', dist, a1, a2, dist, a1, a2);
invcdf = @(x) sprintf('icdf(''%s'', x, %10.10g, %10.10g)', dist, a1, a2);
This anonymous function does not call icdf on its inputs. It create a string that contains the icdf call that you would execute to compute the icdf. [The same holds for prob and cdf.] Don't use sprintf.
invcdf = @(x) icdf(dist, x, a1, a2);
If you really need the %10.10g behavior, use round on a1 and a2.
  2 Comments
SugerCodeCude
SugerCodeCude on 3 Feb 2021
Thank you Steven Lord, the fix on the anonymous function is alot clean, then for the issue on the error I get a matlab with the statistics needed to run chi-square directly.
I was looking to write the chi-square equation, however as time is of the essence I shell do that at a later time.
Thank you again

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More Answers (1)

dpb
dpb on 3 Feb 2021
W/O the Statistics TB, you'll have to resort to some other way to compute the wanted distribution quantities -- a quick look at File Exchange located <generalized-chi-square-distribution> that purports to do what you want. There may be others there.
  2 Comments
dpb
dpb on 3 Feb 2021
Answers is totally volunteer; there are a number like Steven who are TMW employees who contribute, but I am just a retired geezer... :)

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