Looked at the code you posted at Linux questions, but got distracted by what is code and what is commented out.

But the bigger question remained: why are you not using a modern library like MTL4, or highly optimized one Intel MKL? I would not want to start with a library that immediately puts you 20 years behind AND doesn't integrate well with modern software and DevOps.

Dear Theodore, thanks for your reply, which makes perfect sense. MTL4 is written in C++, so I would try that last. A highly optimized Intel MKL, can't be, since my advisors don't want to spend the money on it. NOW, my question basically is: regarless of the fact that ScaLAPACK, as downloaded from NetLib, is old, it certainly gives me scalable results. So why can't I find a C code, calling it, to solve a banded system? I also want to try SPIKE, which has not been my first choice, simply because my advisors are allergic to proprietary code.