This is a toy code which tests the effectiveness of vector instructions on a Runge-Kutta-Fehlberg (RKF45) explicit adaptive integrator. It integrates independent ODEs in different SIMD lanes. It does NOT integrate coupled systems of ODEs. The code requires CMake (version >= 2.8.11) to build. To build the code, create a new directory somewhere, and type cd /path/to/new/directory FC=your_favorite_fortran_compiler cmake /path/to/SIMD_stiff_ODE The executable will be called "main" and lives in /path/to/new/directory/src/