No, it is not difficult. It is way more than that. It is frustrating and depressing according to my experience attempting to modernize a FORTRAN 77 codebase (I gave up finally). Navigating through a quagmire of GOTO statements felt like a desperate endeavor. It's hard to fathom how someone could work on such a project for three years, especially if it appears to be a solo effort.
Upon examining the original FORTRAN code and accompanying papers, I realized that the complexity of the task was far from trivial. Working alone for three years, especially on such a complex codebase, requires a significant amount of dedication and perseverance.
“Renowned for their robustness and efficiency, these solvers are used in a wide
spectrum of applications, for instance, aeronautical engineering [25], astronomy [39], computer
vision [33], robotics [40], and statistics [5].” These algorithms seem truly used in science and engineering.
[5] D. M. Bates, M. Mächler, B. Bolker, and S. Walker. Fitting linear mixed-effects models
using lme4. J. Stat. Softw., 67:1–48, 2015.
[25] F. Gallard et al. GEMS: a Python library for automation of multidisciplinary design
optimization process generation. In 2018 AIAA/ASCE/AHS/ASC Structures, Structural
Dynamics, and Materials Conference, Kissimmee, FL, USA, 2018. AIAA.
[33] H. Izadinia, Q. Shan, and S. M. Seitz. IM2CAD. In Proceedings of the IEEE Conference
on Computer Vision and Pattern Recognition, pages 5134–5143, San Juan, PR, USA, 2017.
IEEE.
[40] K. Mombaur, A. Truong, and J. P. Laumond. From human to humanoid locomotion—an
inverse optimal control approach. Auton. Robot., 28:369–383, 2010.
[39] G. A. Mamon, A. Biviano, and G. Boué. MAMPOSSt: modelling anisotropy and mass
profiles of observed spherical systems I. Gaussian 3D velocities. Mon. Not. R. Astron. Soc.,
429:3079–3098, 2013.
This is truly impressive! While I'm not well-versed in these specific techniques, I do recall learning about Powell during a mathematics course in the past. It's reassuring to know that capable individuals are maintaining his work.
Some time ago, I attempted to update an antiquated FORTRAN program for a particular project, but regrettably, I had to abandon the effort. Navigating the labyrinth of countless GOTO statements was both challenging and disheartening. I became genuinely concerned about the potential impact on my mental well-being.
That being said, I have a profound admiration for the individual who successfully modernized such a complex FORTRAN project. Their achievement is undoubtedly commendable!
