Born 1936. Physicist. Retired from Delft Univ Technology. Active gfortran-/
opencoarrays-user. Presently adapting https://github.com/raullaasner/gadfit version 1.3 (NOT version 1.4 which has been converted to C++ apart from the co-array part). GADfit 1.3 is based on object-oriented Fortran 2018; it applies automatic differentiation, co-arrays, etc. To this I add accommodation of physical prior knowledge in the Jacobian and complex-valued numbers. This is hard for an autodidact programmer, alone in a home-office.