Implement div(E) diagnostics for spectral case (#720)

* Implement div(E) diagnostics for spectral case.

* split travis tests in bigger matrix

* split more TravisCI tests, add electrostatic, use defaults values

* typo

* Move computation of div(E) to base class SpectralBaseAlgorithm.

* need to split psatd too

* consistent variable names and use function to avoid duplication

* fix typo for qed tests

* typo

* also need to update run_tests.sg

* Update copyright tags.

* change matrix

* Add test of div(E) vs rho/epsilon_0 in PML test.

* SpectralFieldIndex: reuse memory slot for Bx when computing divE.

Co-authored-by: MaxThevenet <mthevenet@lbl.gov>

1 files changed, 5 insertions, 3 deletions

diff --git a/Source/FieldSolver/SpectralSolver/SpectralFieldData.H b/Source/FieldSolver/SpectralSolver/SpectralFieldData.H
index 2c5a45faa..db3979796 100644
--- a/Source/FieldSolver/SpectralSolver/SpectralFieldData.H
+++ b/Source/FieldSolver/SpectralSolver/SpectralFieldData.H
@@ -20,10 +20,12 @@
 // Declare type for spectral fields
 using SpectralField = amrex::FabArray< amrex::BaseFab <Complex> >;
 
-/** Index for the regular fields, when stored in spectral space */
+/** Index for the regular fields, when stored in spectral space:
+ *  - n_fields is automatically the total number of fields
+ *  - divE reuses the memory slot for Bx, since Bx is not used when computing divE
+ */
 struct SpectralFieldIndex {
-  enum { Ex=0, Ey, Ez, Bx, By, Bz, Jx, Jy, Jz, rho_old, rho_new, n_fields };
-  // n_fields is automatically the total number of fields
+  enum { Ex=0, Ey, Ez, Bx, By, Bz, Jx, Jy, Jz, rho_old, rho_new, n_fields, divE=3 };
 };
 
 /** Index for the PML fields, when stored in spectral space */