Symmetries for Grid Functions

If your problem and initial data allow it, CartGrid3D allows you to enforce even or odd parity for any grid function at (across) each coordinate axis. For a function $\phi(x,y,z)$, even parity symmetry on the $x$-axis means

$$\phi(-x,y,z) = \phi(x,y,z)$$

while odd parity symmetry means

$$\phi(-x,y,z) = -\phi(x,y,z)$$

Note that the symmetries will only be enforced if a symmetry domain is chosen (that is, if grid::domain is set to something other than grid::domain = "full".