Merge pull request #133 from dalesteam/make-fftw-default

Enable FFTW by default

It is still possible to compile without the FFTW library, with `cmake -DUSE_FFTW=False`
If FFTW is compiled in, it is used by default, `solver_id = 100`. If it is not compiled in the default is `solver_id = 0`, i.e. the old FFT.

.github/workflows/compile.yml

@@ -22,7 +22,6 @@ jobs:
       fail-fast: false
       matrix:
         toolchain: ["gnu", "intel"]
-        fftw:    ["", "-DUSE_FFTW=T"]
         hypre:   ["", "-DUSE_HYPRE=T"]
 
     # Steps represent a sequence of tasks that will be executed as part of the job

.github/workflows/precision.yml

@@ -19,7 +19,6 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        fftw:    ["", "-DUSE_FFTW=T"]
         hypre:    ["", "-DUSE_HYPRE=T"]
         field_r: ["32","64"]
         pois_r:  ["32","64"]

CMakeLists.txt

@@ -216,7 +216,7 @@ endif(NETCDF_FORTRAN_LIB)
 OPTION(USE_HYPRE "Also build iterative solver (optional, needs HYPRE)" OFF)
 
 ### FFTW based poisson solver (FFTW)
-OPTION(USE_FFTW "Also build FFTW based poisson solver (optional, needs FFTW3)" OFF)
+OPTION(USE_FFTW "Also build FFTW based poisson solver (optional, needs FFTW3)" ON)
 
 ### NVTX
 OPTION(USE_NVTX "Enable GPU profiling" OFF)

src/modglobal.f90

@@ -155,7 +155,11 @@ module modglobal
       logical :: lconstexner = .false.  !<  switch to use the initial pressure profile in the exner function
 
       ! Poisson solver: modpois / modhypre
-      integer :: solver_id = 0       ! Identifier for nummerical solver:    0    1   2     3       4
+#ifdef USE_FFTW
+      integer :: solver_id = 100     ! Identifier for nummerical solver:    0    1   2     3       4
+#else
+      integer :: solver_id = 0
+#endif
                                      !                                     FFT  SMG PFMG BiCGSTAB GMRES
       integer :: maxiter = 10000     ! Number of iterations                 .    X   X     X       X
       real(real64):: tolerance = 1E-8! Convergence threshold                .    X   X     X       X

src/modpois.f90

@@ -58,8 +58,7 @@ subroutine initpois
     implicit none
 
     if (solver_id == 0) then
-      ! FFT based solver
-      call fft2dinit(p, Fp, d, xyrt, ps,pe,qs,qe)
+      call fft2dinit(p, Fp, d, xyrt, ps, pe, qs, qe)
     else if (solver_id == 100) then
       ! FFTW based solver
       call fftwinit(p, Fp, d, xyrt, ps,pe,qs,qe)
@@ -101,7 +100,6 @@ subroutine exitpois
     implicit none
 
     if (solver_id == 0) then
-      ! FFT based solver
       call fft2dexit(p,Fp,d,xyrt)
     else if (solver_id == 100) then
       ! FFTW based solver