RZ: Use WarpX::ncomps more consistently (#2951)

* RZ: Use WarpX::ncomps more consistently

We used `2*modes - 1` in many places, which is harder to follow then
the variable we have.

* Update Comments

* Replace leftover `ncomp` -> `m_ncomps`

1 files changed, 3 insertions, 3 deletions

diff --git a/Source/FieldSolver/FiniteDifferenceSolver/EvolveF.cpp b/Source/FieldSolver/FiniteDifferenceSolver/EvolveF.cpp
index 18401d74e..f5bd3781f 100644
--- a/Source/FieldSolver/FiniteDifferenceSolver/EvolveF.cpp
+++ b/Source/FieldSolver/FiniteDifferenceSolver/EvolveF.cpp
@@ -171,11 +171,11 @@ void FiniteDifferenceSolver::EvolveFCylindrical (
         Real constexpr c2 = PhysConst::c * PhysConst::c;
 
         // Use the right shift in components:
-        // - the first 2*n_rz_azimuthal_modes-1 components correspond to rho old (i.e. rhocomp=0)
-        // - the next 2*n_rz_azimuthal_modes-1 components correspond to rho new (i.e. rhocomp=1)
+        // - the first WarpX::ncomps (2*n_rz_azimuthal_modes-1) components correspond to rho old (i.e. rhocomp=0)
+        // - the next WarpX::ncomps (2*n_rz_azimuthal_modes-1) components correspond to rho new (i.e. rhocomp=1)
         int rho_shift = 0;
         if (rhocomp == 1) {
-            rho_shift = 2*WarpX::n_rz_azimuthal_modes-1;
+            rho_shift = WarpX::ncomps;
         }
 
         // Loop over the cells and update the fields