Why do I receive the error message 'CDF must not have duplicate X values' while using the KTEST function from the Statistics Toolbox 6.0 (R2007a)?

I use the result of an ECDF computation as input for KTEST:

n=20;

[f,x] = ecdf(rand(1,n));

d=diff(sort(x));

[h,p] = kstest(rand(1,n),[x f], 0.05);

I receive the following error:

 ??? Error using ==> kstest at 138

 CDF must not have duplicate X values.

Answer 1

[MathWorks Support Team]

The error message is caused by the fact that the first two elements of the ouput 'x' of the function ECDF are identical.

To workaround the error message use 'x(2:end)' as input data instead. You may have to change the size of other parameters too, e.g. size of F.