Compiling with PETSc support Fails

[TomGoffrey]

The Makefile doesn't automatically pick up the required PETSc flags.

Looking at the Makefile I'm assuming variables such as PETSC_DIR should be set.

The use of pkg-config removes the requirement of the user to set these variable:

$ git diff Makefile
diff --git a/epoch1d/Makefile b/epoch1d/Makefile
index 50acc5db..32d943e0 100644
--- a/epoch1d/Makefile
+++ b/epoch1d/Makefile
@@ -376,11 +376,13 @@ main: $(FULLTARGET)
 endif

 #PETSc
--include $(PETSC_DIR)/lib/petsc/conf/variables
--include $(PETSC_DIR)/lib/petsc/conf/rules
-CFLAGS = $(PETSC_CC_INCLUDES)
-FFLAGS += $(PETSC_FC_INCLUDES) -fopenmp
-LDFLAGS +=$(PETSC_LIB)
+PETSC_GOT := $(shell pkg-config --exists PETSc && echo 0)
+ifeq ($(PETSC_GOT),0)
+  PETSC_FFLAGS := $(shell pkg-config --cflags PETSc)
+  PETSC_LDFLAGS := $(shell pkg-config --libs PETSc)
+  FFLAGS += $(PETSC_FFLAGS)
+  LDFLAGS += $(PETSC_LDFLAGS)
+endif

[michelosca]

Using pkg-config does not work for me. When adding it I get the following error when compiling

$ make COMPILER=gfortran
mpif90 -c -O3 -g -std=f2003 -ffpe-summary=invalid,zero,overflow -I../SDF/FORTRAN/include -Iobj -Jobj -I/usr/include  -o obj/electrostatic.o  -DPER_SPECIES_WEIGHT -DELECTROSTATIC -DNEUTRAL_COLLISIONS -DPETSC -DSEE -DPART_PERP_POSITION -D_COMMIT='"v4.17.14-386-g8a55b28e-dirty"' -D_DATE=1706880367 -D_MACHINE='"login1.viking2.yor.alces.network"' -Isrc/include src/physics_packages/electrostatic.F90
src/physics_packages/electrostatic.F90:22:6:

   22 |   USE petscvec
      |      1
Fatal Error: Cannot open module file ‘petscvec.mod’ for reading at (1): No such file or directory
compilation terminated.
make[1]: *** [Makefile:416: electrostatic.o] Error 1
make[1]: Leaving directory '/mnt/scratch/users/moe505/epoch/epoch1d'
make: *** [Makefile:474: commit] Error 2

I do not get this error when using the current setup. Note that the right Makefile is the one in the epoch_ltp_1d branch.

[TomGoffrey]

Looks to me like pkgconfig can't find your PETSc installation. I've always used this method when including PETSc - given it's listed as the recommended method on the getting started page:

https://petsc.org/release/manual/getting_started/

Suspect you need to add the PETSc location to your PKG_CONFIG_PATH variable.

Don't have strong preference for which option we go for (beyond following PETSc's own recommendations), but should be documented.