Generate C/C++ code from tensor expression and so on (using xAct)

• Install free Wolfram Engine for Devolopers from https://www.wolfram.com/developer/. (If you are rich, you can install the totally worth-it Mathematica instead, versions that support 'wolframscript'.)

• Download xAct from http://www.xact.es and install it properly.

• clone repo: git clone [email protected]:lwJi/Generato.git

• set enviroment variable: export GENERATO="/your/repo/path"

• Small toy

wolframscript -f test/unit/test.wl

• GHG formulation of Einstein's equations

Please take a look at the example script for GHG system: test/integration/GHG_rhs.ipynb. Or

wolframscript -f test/integration/GHG_rhs.wl

• Use lower case to name variables (to aviod conflict with say Pi)

• Use SetEQNDelayed if your right-hand side (rhs) includes an If statement to handle different component cases. Otherwise, SetEQN is preferred because it has an option, CheckRHS, which checks if all the terms appearing in the rhs are well-defined.

• IsDefined[term] is very useful for debugging.