Hi, I believe I have corrected most of the issues brought up by Pauli with the multivariate code. I have not merged the python callback machinery as of now, but that can still be done. I ran my c code through indent using the suggested command to fix formatting issues, removed printfs, fixed comments, added some documentation, and check the return value of c_array_from_tuple. I added a few test cases showing the accuracy of solutions and increase in speed. Unfortunately the unusual function signature means that I cannot use built-in c library functions, so I created the test_multivariate.c file that must be compiled to run the tests. I know this can be built into the process, but I was unsure of how to do that, so I currently only run these tests on a linux system. Please let me know what else I can do to get this merged as soon as possible. Thanks, Brian