Mathomatic is written to do most symbolic manipulations with memory moves, like an assembly language program. This causes Mathomatic to crash when used with the new LLVM backend, which doesn't seem to like the standard C library function memmove(3). To use Mathomatic with a C compiler that uses an LLVM backend, disable all optimizations with "-O0" on the C compiler command line. Otherwise the regression tests will loop endlessly. This is most certainly an optimization bug in LLVM. To help those trying to debug this optimization error, Mathomatic will fail when LLVM optimizes the simplification of (32^.5) to 4*(2^.5), and the like, going into an endless loop every time.