for PETSc v3.17.3

C codes (Chapters 1--12) were tested with PETSc 3.17.3 (v3.17.3 tag, commit )

Python codes (Chapters 13--14) were tested with Firedrake commit e5c4aa61

Gmsh version 4.9.3 (and 4.9.0)

Test machine: thelio ubuntu 20.04