Legacy Fortran atmospheric physics moves to GPU: four LLMs each wrote a JAX version, and the fastest ran about 357 times faster than serial Fortran
Four LLMs rewrote the Kessler warm-rain microphysics Fortran code into GPU-executable JAX, reproducing the Fortran reference to near floating-point precision while differing widely in GPU performance, with the fastest reaching about 357 times the speed of serial Fortran in cached GPU execution.