Created attachment 1997 [details]
EmpiricalVariable patch

If the provided empirical CDF contains negative values in the X axis this function will always report an error (and it should not).

This issue can be reproduced like this: 

  EmpiricalRandomVariable uv;

  uv.CDF(-0.1,0.1);
  uv.CDF(0, 0.2);
  uv.CDF(0.1, 0.3);

  uv.GetValue();


The problem is: 

Line 1601: if (current.value < prior.value || current.cdf < prior.cdf)

Which is true in the first iteration because the "prior" variable is initialized by its default constructor:

Line 1597:  ValueCDF prior;

Which sets prior.value = 0 and prior.cdf = 0.

A possible fix would be to assign the first element of the empirical distribution:

Line 1597:  ValueCDF prior = emp[0];