Avoid copying matrices

Author: ax3l

src/particles/diagnostics/CovarianceMatrixMath.H

@@ -161,7 +161,7 @@ namespace impactx::diagnostics
      */
     amrex::ParticleReal
     TraceMat (
-        amrex::Array2D<amrex::ParticleReal, 1, 6, 1, 6> A
+        amrex::Array2D<amrex::ParticleReal, 1, 6, 1, 6> const & A
     )
     {
         int const dim = 6;
@@ -182,8 +182,8 @@ namespace impactx::diagnostics
      */
     amrex::Array2D<amrex::ParticleReal, 1, 6, 1, 6>
     MultiplyMat (
-        amrex::Array2D<amrex::ParticleReal, 1, 6, 1, 6> A,
-        amrex::Array2D<amrex::ParticleReal, 1, 6, 1, 6> B
+        amrex::Array2D<amrex::ParticleReal, 1, 6, 1, 6> const & A,
+        amrex::Array2D<amrex::ParticleReal, 1, 6, 1, 6> const & B
     )
     {
         amrex::Array2D<amrex::ParticleReal, 1, 6, 1, 6> C;

src/particles/diagnostics/EmittanceInvariants.H

@@ -43,7 +43,7 @@ namespace impactx::diagnostics
             amrex::ParticleReal,
             amrex::ParticleReal>
     KineticInvariants (
-        amrex::Array2D<amrex::ParticleReal, 1, 6, 1, 6> Sigma
+        amrex::Array2D<amrex::ParticleReal, 1, 6, 1, 6> const & Sigma
     );
 
     /** Returns the three eigenemittances
@@ -68,7 +68,7 @@ namespace impactx::diagnostics
             amrex::ParticleReal,
             amrex::ParticleReal>
     Eigenemittances (
-        amrex::Array2D<amrex::ParticleReal, 1, 6, 1, 6> Sigma
+        amrex::Array2D<amrex::ParticleReal, 1, 6, 1, 6> const & Sigma
     );
 
 } // namespace impactx::diagnostics

src/particles/diagnostics/EmittanceInvariants.cpp

@@ -37,7 +37,7 @@ namespace impactx::diagnostics
             amrex::ParticleReal,
             amrex::ParticleReal>
     KineticInvariants (
-        amrex::Array2D<amrex::ParticleReal, 1, 6, 1, 6> Sigma
+        amrex::Array2D<amrex::ParticleReal, 1, 6, 1, 6> const & Sigma
     )
     {
         using namespace amrex::literals;
@@ -98,7 +98,7 @@ namespace impactx::diagnostics
             amrex::ParticleReal,
             amrex::ParticleReal>
     Eigenemittances (
-        amrex::Array2D<amrex::ParticleReal, 1, 6, 1, 6> Sigma
+        amrex::Array2D<amrex::ParticleReal, 1, 6, 1, 6> const & Sigma
     )
     {
         BL_PROFILE("impactx::diagnostics::Eigenemittances");