PSATD Single precision (#805)

* fix compilation for single precision PSATD with USE_GPU

* compiles and tested on CPU also

* add sentence to doc: FFTW needs to be compiled with single precision option

* add test, better pre-proc directives indent, clearer ifdef

* use using whenever possible

* indent

* fix TravisCI matrix, and improve matrix test

* need to compile with same precision for fields and particles

1 files changed, 1 insertions, 1 deletions

diff --git a/Source/FieldSolver/SpectralSolver/SpectralKSpace.cpp b/Source/FieldSolver/SpectralSolver/SpectralKSpace.cpp
index 9f4e9b7c8..c1e0c59d0 100644
--- a/Source/FieldSolver/SpectralSolver/SpectralKSpace.cpp
+++ b/Source/FieldSolver/SpectralSolver/SpectralKSpace.cpp
@@ -153,7 +153,7 @@ SpectralKSpace::getSpectralShiftFactor( const DistributionMapping& dm,
         }
         const Complex I{0,1};
         for (int i=0; i<k.size(); i++ ){
-            shift[i] = exp( I*sign*k[i]*0.5*dx[i_dim]);
+            shift[i] = exp( I*sign*k[i]*0.5_rt*dx[i_dim]);
         }
     }
     return shift_factor;