Add macOS (gfortran) build support

.gitignore

@@ -9,3 +9,11 @@ libfvcom.a
 *.mod
 *.o
 *.f90
+
+# Compiled libraries and install directory
+libs/install/
+libs/julian/
+libs/metis/build/
+
+# Project documentation (user-specific)
+CLAUDE.md

docs/BUILD_MACOS.md

@@ -0,0 +1,152 @@
+# Building FVCOM on macOS (Apple Silicon / Intel)
+
+This guide describes how to build FVCOM on macOS using gfortran and OpenMPI.
+
+## Prerequisites
+
+Install required dependencies via Homebrew:
+
+```bash
+brew install gcc open-mpi netcdf netcdf-fortran hdf5 metis
+```
+
+## Configuration (make.inc)
+
+A macOS configuration template is provided at `src/make-mac.inc`. To use it:
+
+```bash
+cd src
+cp make-mac.inc make.inc
+```
+
+Then edit `make.inc` with your specific paths:
+
+**OR** manually edit `src/make.inc` with the following changes:
+
+### 1. Set paths
+
+```makefile
+TOPDIR = /path/to/FVCOM/src
+INSTALLDIR = /path/to/FVCOM/libs/install
+```
+
+### 2. Enable LOCAL INSTALL
+
+```makefile
+LIBDIR = -L$(INSTALLDIR)/lib
+INCDIR = -I$(INSTALLDIR)/include
+```
+
+### 3. Configure NetCDF (Homebrew paths)
+
+```makefile
+IOLIBS = -L/opt/homebrew/lib -lnetcdff -lnetcdf
+IOINCS = -I/opt/homebrew/include
+```
+
+### 4. Configure METIS (Homebrew paths)
+
+```makefile
+FLAG_411 = -DMETIS_5
+PARLIB =
+PARTINCS = -I/opt/homebrew/include
+PARTLIBS = -L/opt/homebrew/lib -lmetis
+```
+
+### 5. Use gfortran/OpenMPI compiler
+
+Comment out the Intel compiler section and add:
+
+```makefile
+CPP      = /usr/bin/cpp
+COMPFLAG = -DGFORTRAN
+CC       = mpicc
+CXX      = mpicxx
+CFLAGS   = -O3
+FC       = mpif90
+DEBFLGS  =
+OPT      = -O3 -ffree-line-length-none
+CLIB     =
+```
+
+## Building the Julian Library
+
+The Julian library requires a fix for Fortran name mangling on macOS with gfortran.
+
+### Fix fortran.h
+
+Edit `libs/julian/fortran.h` and remove the `__APPLE__` special case for `FORTRAN_NAME`:
+
+**Before:**
+```c
+#ifdef __APPLE__
+#define FORTRAN_NAME(name)  name
+
+#else
+
+#ifdef __STDC__
+#define FORTRAN_NAME(name)  name##_
+...
+```
+
+**After:**
+```c
+#ifdef __STDC__
+#define FORTRAN_NAME(name)  name##_
+
+#else
+#define FORTRAN_NAME(name)  name/**/_
+
+#endif
+#endif
+```
+
+This ensures gfortran's expected trailing underscore convention is used.
+
+### Build and install Julian
+
+```bash
+cd libs/julian
+make clean
+make libjulian
+
+# Install to libs/install
+mkdir -p ../install/lib ../install/include
+cp libjulian.a ../install/lib/
+cp fjulian.inc ../install/include/
+```
+
+## Building FVCOM
+
+```bash
+cd src
+
+# Clean previous build
+make clean
+
+# Manually compile partition.c (workaround for makefile issue)
+mpicc -c -O3 -I/opt/homebrew/include partition.c
+
+# Build FVCOM
+make
+```
+
+## Known Issues
+
+### 1. partition.c not compiled automatically
+
+The makefile's `ifdef FLAG_411` check occurs before `make.inc` is included, so `partition.c` may not be compiled. Compile it manually as shown above.
+
+### 2. Parallel make race condition
+
+Using `make -j` may cause race conditions with module dependencies. If you encounter "Cannot open module file" errors, run `make` without the `-j` flag.
+
+## Verification
+
+Test the build:
+
+```bash
+./fvcom --help
+```
+
+You should see the FVCOM help message with available options.

src/make-mac.inc

@@ -0,0 +1,188 @@
+#/===========================================================================/
+# macOS Configuration Template for FVCOM
+#
+# This is a reference configuration for building FVCOM on macOS (Apple Silicon
+# and Intel) using gfortran and OpenMPI from Homebrew.
+#
+# To use this template:
+# 1. Copy this file: cp make-mac.inc make.inc
+# 2. Edit the TOPDIR and INSTALLDIR paths below
+# 3. Adjust library paths if your Homebrew installation differs
+# 4. Run: make clean && make
+#
+# See docs/BUILD_MACOS.md for detailed build instructions
+#/===========================================================================/
+
+#========== TOPDIR ========================================================
+# TOPDIR is the directory in which this make file and the fvcom source reside
+# !!! CHANGE THIS TO YOUR ACTUAL PATH !!!
+
+           TOPDIR        = /path/to/FVCOM/src
+
+#========== INSTALLDIR =====================================================
+# INSTALLDIR is where you installed the Julian library
+# !!! CHANGE THIS TO YOUR ACTUAL PATH !!!
+
+           INSTALLDIR    = /path/to/FVCOM/libs/install
+
+#===========================================================================
+# PREPROCESSOR OPTIONS FOR CPP
+           DEF_FLAGS     = -P -traditional
+
+#===========================================================================
+# MEDM ENVIRONMENT - Use environmental variables if set
+colon=:
+empty=
+dashI= $(empty) -I
+dashL= $(empty) -L
+
+ifeq ($(origin LIBPATH), environment)
+  LIBDIR = -L$(subst $(colon),$(dashL),$(LIBPATH))
+endif
+ifeq ($(origin INCLUDEPATH), environment)
+  INCDIR = -I$(subst $(colon),$(dashI),$(INCLUDEPATH))
+endif
+
+#===========================================================================
+# LOCAL INSTALL - Point to your local Julian library installation
+           LIBDIR       =  -L$(INSTALLDIR)/lib
+           INCDIR       =  -I$(INSTALLDIR)/include
+
+#--------------------------------------------------------------------------
+#	STANDARD LIBRARIES FOR DATA AND TIME
+	   DTLIBS	= -ljulian
+	   DTINCS	=
+
+#--------------------------------------------------------------------------
+#        NETCDF - Homebrew paths for Apple Silicon
+#        For Intel Mac, change /opt/homebrew to /usr/local
+#--------------------------------------------------------------------------
+           FLAG_USE_NETCDF4     = -DUSE_NETCDF4
+#          FLAG_USE_COMPRESSION = -DUSE_COMPRESSION
+           IOLIBS       =  -L/opt/homebrew/lib -lnetcdff -lnetcdf
+           IOINCS       =  -I/opt/homebrew/include
+
+#==========================================================================
+#  MODEL OPTIONS - Typical configuration for development/testing
+#==========================================================================
+
+# PRECISION - Double precision with single precision output
+           FLAG_1 =  -DDOUBLE_PRECISION -DSINGLE_OUTPUT
+
+# SPHERICAL COORDINATES
+           FLAG_2 = -DSPHERICAL
+
+# WET/DRY TREATMENT
+           FLAG_3 = -DWET_DRY
+
+# MPI PARALLELIZATION with METIS 5
+           FLAG_4 = -DMULTIPROCESSOR
+           FLAG_411 = -DMETIS_5
+           PARLIB =
+           PARTINCS = -I/opt/homebrew/include
+           PARTLIBS = -L/opt/homebrew/lib -lmetis
+
+# WATER QUALITY MODEL (uncomment to enable)
+#          FLAG_5 = -DWATER_QUALITY
+
+# PROJECTION (uncomment to enable)
+#          FLAG_6 = -DPROJ
+#          PROJLIBS       = -lfproj4 -lproj -lm
+#          PROJINCS       =
+
+# DATA ASSIMILATION (uncomment to enable, requires PETSc)
+#          FLAG_7 = -DDATA_ASSIM
+#          include ${PETSC_DIR}/bmake/common/variables
+#          OILIB  = -lmkl_lapack -lmkl_em64t -lguide -lpthread
+
+# ADVECTION LIMITER - Choose ONE (REQUIRED)
+           FLAG_8 =  -DLIMITED_NO
+#          FLAG_8 =  -DLIMITED_1
+#          FLAG_8 =  -DLIMITED_2
+
+# SEMI-IMPLICIT (uncomment to enable, requires PETSc)
+#          FLAG_9 = -DSEMI_IMPLICIT
+#          include ${PETSC_DIR}/bmake/common/variables
+
+# SOLID BOUNDARY TREATMENT - Choose ONE (REQUIRED)
+           FLAG_10  = -DGCN
+#          FLAG_10  = -DGCY1
+#          FLAG_10 = -DGCY2
+
+# GOTM TURBULENCE MODEL (uncomment to enable)
+#          FLAG_11 = -DGOTM
+#          GOTMLIB       = -L../GOTM_source -lturbulence -lutil
+#          GOTMINCS      = -I../GOTM_source
+
+# EQUILIBRIUM TIDE (uncomment to enable)
+#          FLAG_12 = -DEQUI_TIDE
+
+# ATMOSPHERIC TIDE (uncomment to enable)
+#          FLAG_13 = -DATMO_TIDE
+
+# RIVER DISTRIBUTION (uncomment for old-style floating point)
+#          FLAG_14 = -DRIVER_FLOAT
+
+# TVD (Total Variational Diminishing) - Recommended for better accuracy
+           FLAG_44 = -DTVD
+
+# MPDATA SCHEME
+           FLAG_15 = -DMPDATA
+
+# ADDITIONAL OPTIONS (uncomment as needed)
+#          FLAG_16 = -DLAG_PARTICLE
+#          FLAG_17 = -DDYE_RELEASE
+#          FLAG_18 = -DTWO_D_MODEL
+#          FLAG_19 = -DICE
+#          FLAG_20 = -DICE_EMBEDDING
+#          FLAG_21 = -DSEDIMENT
+#          FLAG_22 = -DSED_CSTMS
+#          FLAG_23 = -DOFFLINE_BIOLOGY
+#          FLAG_24 = -DOFFLINE_SEDIMENT
+#          FLAG_25 = -DVISIT
+#          FLAG_26 = -DVIS_OMVIZ
+#          FLAG_27 = -DBIO_CALC
+#          FLAG_28 = -DPROBES
+#          FLAG_29 = -DSTATION_TIMESERIES
+#          FLAG_30 = -DBALANCE_2D
+#          FLAG_31 = -DENKF
+#          FLAG_32 = -DENKF_DETAILS
+#          FLAG_33 = -DRRKASSIM
+#          FLAG_34 = -DTIGHT_COUPLING
+#          FLAG_35 = -DONE_D_TIDEBC
+#          FLAG_36 = -DBALANCE_2D_VIA_FVCOM
+#          FLAG_37 = -DBALANCE_3D_VIA_OCEAN
+#          FLAG_38 = -DDTI_RESET_S
+#          FLAG_39 = -DDTI_RESET_M
+#          FLAG_40 = -DNESTING
+#          FLAG_41 = -DMEAN_FLOW_RIVER
+#          FLAG_42 = -DPLBC
+#          FLAG_43 = -DDAM_BREAK
+#          FLAG_45 = -DFLUID_MUD
+#          FLAG_46 = -DOUT_STATION
+#          FLAG_47 = -DOUT_SPARSE
+#          FLAG_48 = -DDOUBLE_ECHO
+#          FLAG_49 = -DBOUNDSCHK
+#          FLAG_50 = -DESMF_NESTING
+#          FLAG_51 = -DFLOCMOD
+#          FLAG_52 = -DTPXO_TIDE
+#          FLAG_53 = -DMLD_RHO
+#          FLAG_54 = -DVEGETATION
+#          FLAG_55 = -DSEDIMENT_HEATING
+
+#--------------------------------------------------------------------------
+#  gfortran/OpenMPI Compiler Configuration (Homebrew)
+#--------------------------------------------------------------------------
+         CPP      = /usr/bin/cpp
+         COMPFLAG = -DGFORTRAN
+         CC       = mpicc
+         CXX      = mpicxx
+         CFLAGS   = -O3
+         FC       = mpif90
+         DEBFLGS  =
+         OPT      = -O3 -ffree-line-length-none
+         CLIB     =
+
+#==========================================================================
+#  END OF USER CONFIGURATION
+#==========================================================================

src/swancom5.F

@@ -118,19 +118,23 @@ SUBROUTINE SWAPAR1(I,IS,ID,DEP2,KWAVEL,CGOL)
   IMPLICIT NONE                                                     
 !
   INTEGER :: IC,IS,ID,I,INDX
-  REAL    :: NN(1:MSC), ND(1:MSC)                                    
+  REAL    :: NN(1:MSC), ND(1:MSC)
   REAL    :: DEP2(MT),KWAVEL,CGOL
-  REAL    :: DEPLOC,SPCSIGL
+  REAL    :: DEPLOC
+  ! Local arrays for KSCIP1 interface (gfortran compatibility)
+  REAL    :: SPCSIGL(1),KWAVEL_ARR(1),CGOL_ARR(1),NNL(1),NDL(1)
 
   DEPLOC = (DEP2(NV(I,1))+DEP2(NV(I,2))+DEP2(NV(I,3)))/3.0
   IF(DEPLOC <= DEPMIN)THEN
 !   *** depth is negative ***
-    KWAVEL = -1.                                           
-    CGOL   = 0.                                            
+    KWAVEL = -1.
+    CGOL   = 0.
   ELSE
 !   *** call KSCIP1 to compute KWAVE and CGO ***
-    SPCSIGL = SPCSIG(IS)
-    CALL KSCIP1(1,SPCSIGL,DEPLOC,KWAVEL,CGOL,NN,ND)                                 
+    SPCSIGL(1) = SPCSIG(IS)
+    CALL KSCIP1(1,SPCSIGL,DEPLOC,KWAVEL_ARR,CGOL_ARR,NNL,NDL)
+    KWAVEL = KWAVEL_ARR(1)
+    CGOL = CGOL_ARR(1)                                 
   END IF
 
   RETURN