If you have a bug in your evaluator program, nl will produce, most probably, the following error:
your program returned 198 verify that your program is a function evaluator program r(198);
The error indicates that your program cannot be evaluated.
The best way to spot any issues in your evaluator program is to run it interactively. You just need to define your sample (usually observations where none of the variables are missing), and a matrix with values for your parameters. Let me show you an example with nlces2. This is the code to fit the CES production function, from the documentation for the nl command: Read more…