Fixed some minor compile issues, made Makefile more obvious

Makefile.reference

@@ -31,7 +31,7 @@
 #
 # - NGRAVS_ACCUMULATOR:
 #     Enable to track the number of particles contained within tree nodes.  This information
-#     is then accurately provided to AccelFxns and SplineFxns for making an accurate monopole 
+#     is then accurately provided to AccelFxns and SplineFxns for making an improved monopole 
 #     approximation in exotic force scenarios.
 #
 # - NGRAVS_L3VIOLATION:
@@ -145,22 +145,9 @@ OPT   +=  -DSYNCHRONIZATION
 CC       = mpicc               # sets the C-compiler
 OPTIMIZE = -g -O3 -Wall
 MPICHLIB = 
-FFTW_INCL= -I/home/twili/research/include
-FFTW_LIBS= -L/home/twili/research/lib
-
-
-#--------------------------------------- Some sample directories
-
-ifeq ($(SYSTYPE),"RZG_LinuxCluster-gcc")
-CC       =  mpiccg
-OPTIMIZE = -O3 -Wall
-GSL_INCL =  -I/afs/rzg/u/vrs/gsl_linux_gcc3.2/include
-GSL_LIBS =  -L/afs/rzg/u/vrs/gsl_linux_gcc3.2/lib  -Wl,"-R /afs/rzg/u/vrs/gsl_linux_gcc3.2/lib"
-FFTW_INCL=  -I/afs/rzg/u/vrs/fftw_linux_gcc3.2/include
-FFTW_LIBS=  -L/afs/rzg/u/vrs/fftw_linux_gcc3.2/lib  
-HDF5INCL =  -I/afs/rzg/u/vrs/hdf5_linux/include
-HDF5LIB  =  -L/afs/rzg/u/vrs/hdf5_linux/lib  -lhdf5 -lz  -Wl,"-R /afs/rzg/u/vrs/hdf5_linux/lib"
-endif
+# Its usually easier to define these in your environment if you need them
+#GADGET2_INCL= -I/home/twili/research/include
+#GADGET2_LIBS= -L/home/twili/research/lib
 
 
 ifneq (HAVE_HDF5,$(findstring HAVE_HDF5,$(OPT))) 
@@ -186,7 +173,7 @@ OBJS   = main.o  run.o  predict.o begrun.o endrun.o global.o  \
 INCL   = allvars.h  proto.h  tags.h  Makefile
 
 
-CFLAGS = $(OPTIONS) $(FFTW_INCL) $(FFTW_LIBS)
+CFLAGS = $(OPTIONS) $(GADGET2_INCL) $(GADGET2_LIBS)
 
 
 ifeq (NOTYPEPREFIX_FFTW,$(findstring NOTYPEPREFIX_FFTW,$(OPT)))    # fftw installed with type prefix?

ngravs.c

@@ -821,7 +821,8 @@ double ewald_psi(double x[3])
  double coloyuk(double target, double source, double h, double r, long N) {
    return yukawa(target, source, h, r, N) + newtonian(target, source, h, r, N);
  }
-
+
+#ifdef PMGRID
  double pgcoloyuk(double target, double source, double k2, double k, long N) {
    return pgyukawa(target, source, k2, k, N) + pgdelta(target, source, k2, k, N);
  }
@@ -830,6 +831,7 @@ double ewald_psi(double x[3])
 
    return normed_pgyukawa(target, source, k2, k, N) + normed_pgdelta(target, source, k2, k, N);
  }
+#endif
 
  void coloyuk_lattice_force(int iii, int jjj, int kkk, double x[3], double force[3]) {
 
@@ -856,6 +858,9 @@ double ewald_psi(double x[3])
 /*! A periodic yukawa k-space Greens function, normalized by the Newtonian interaction
  *  NOTE: k is supplied dimensionlessly in terms of PMGRID so k \in [-PMGRID/2, PMGRID/2]
  */
+#ifdef PMGRID
+// This #ifdef is required because the structures for tracking the smoothing length
+// are not allocated unless running in periodic mode.
 double pgyukawa(double target, double source, double k2, double k, long N) {
 
   double ym = YUKAWA_IMASS/(2*M_PI);
@@ -873,6 +878,7 @@ double normed_pgyukawa(double target, double source, double k2, double k, long N
   double ym = gridKtoNormK(YUKAWA_IMASS/(2*M_PI));
   return k2 / (k2 + ym*ym) * exp(-ym*ym*0.25);
 }
+#endif
 
 /*! This function computes the Madelung constant for the yukawa potential
  * which depends on the box length interestingly...

ngravs_core.c

@@ -21,6 +21,7 @@
  *
  */
 
+#ifdef PMGRID
 struct ngravsInterpolant *ngravsPeriodicTable;
 
 double normKtoGridK(double normk) {
@@ -188,6 +189,7 @@ void ngravsConvolutionFree(struct ngravsInterpolant *s) {
   fftw_destroy_plan(s->plan);
   free(s);
 }
+#endif
 
 //////////////////////// END FOURIER INTEGRATION ROUTINES //////////