Use matlab symbolic engine for calculating gz
Use matlab symbolic engine for calculating gz

3x performance gain

mroyluna/summer17mantlesim,Johnson-A/UNM_Research,mroyluna/summer17mantlesim,Johnson-A/mantle_simulation,mroyluna/summer17mantlesim,Johnson-A/UNM_Research,Johnson-A/mantle_simulation,Johnson-A/UNM_Research