Modernize build system, enable runtime library selection, and add regression testing

.github/workflows/test.yml

@@ -0,0 +1,67 @@
+name: FSPS Regression Tests
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  test-matrix:
+    runs-on: ubuntu-latest
+
+    env:
+      SPS_HOME: ${{ github.workspace }}
+      FSPS_TEST_RTOL: 1.0E-5  # Set global relative tolerance here
+
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          # Define the configurations to test.
+          # 'opts': The library options passed to test_runner.
+          # 'ref_suffix': The suffix of the reference file in tests/data/
+
+          # 1. Standard (Default)
+          - name: MILES + MIST (default)
+            opts: "--isoc mist --spec miles"
+            ref_suffix: "MILES-1_MIST-1"
+
+          # 2. BaSeL+Padova
+          - name: BaSEL + Padova
+            opts: "--isoc pdva --spec basel"
+            ref_suffix: "MILES-0_MIST-0_BASEL-1_PADOVA-1"
+
+          # 3. Dust Model (THEMIS)
+          - name: THEMIS (dust)
+            opts: "--isoc mist --spec miles --dust themis"
+            ref_suffix: "MILES-1_MIST-1_THEMIS-1_DL07-0"
+
+          # 4. C3K
+          - name: C3K + MIST
+            opts: "--isoc mist --spec c3k_afe+0.0"
+            ref_suffix: "MILES-0_C3K-1_MIST-1"
+
+          # 5. BPASS (Different logic path)
+          - name: BPASS
+            opts: "--isoc bpss"
+            ref_suffix: "MIST-0_BPASS-1"
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v3
+
+    - name: Install GFortran
+      run: |
+        sudo apt-get update
+        sudo apt-get install -y gfortran
+
+    - name: Compile FSPS and Test Runner
+      # We force FFLAGS to include the matrix flags + standard flags + silence underflows
+      run: |
+        make clean
+        make test FFLAGS="-cpp -O3 -fPIC -ffpe-summary=invalid,zero,overflow"
+
+    - name: Run Test
+      run: |
+        ./test_runner tests/data/sps_ref_${{ matrix.ref_suffix }}.bin ${{ matrix.opts }}

.gitignore

@@ -1,6 +1,3 @@
-*.o
-*.mod
-*.exe
 .DS_Store
 nr
 SPECTRA/CKC14/*
@@ -11,3 +8,17 @@ metalml.f90
 colorteff.f90
 bytype.f90
 Makefile.prv
+
+# Ignore compiler outputs
+build/
+*.o
+*.mod
+*.exe
+
+# Executables produced by Makefile
+autosps
+simple
+lesssimple
+spec_bin
+generate_test_data
+test_runner

LICENSE

@@ -1,6 +1,6 @@
 The MIT License (MIT)
 
-Copyright (c) 2009-2021 Charlie Conroy & contributors.
+Copyright (c) 2009-2026 Charlie Conroy & contributors.
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

Makefile

@@ -0,0 +1,111 @@
+# ===================================
+# Compiler Configuration
+# ===================================
+
+# Default to gfortran, allow for an override (e.g. make FC=ifort)
+FC = gfortran
+
+# Default flags
+FFLAGS ?= -O3 -cpp -fPIC
+
+# Directory configuration
+SRC_DIR := src
+TEST_DIR := tests
+BUILD_DIR := build
+
+# Module directory flags:
+# Gfortran uses -J to specify where to put/find .mod files
+# Intel (ifort) uses -module. We default to Gfortran syntax here.
+# You can override this: make MOD_FLAG=-module
+MOD_FLAG ?= -J
+
+# Combine flags to include the build dir for .mod search
+FCFLAGS := $(FFLAGS) $(MOD_FLAG)$(BUILD_DIR) -I$(BUILD_DIR)
+
+# ===================================
+# Source and Object Definitions
+# ===================================
+
+# Tell make to look for source files in these directories
+VPATH = $(SRC_DIR):$(TEST_DIR)
+
+# The list of programs to build (executables)
+PROGS = simple lesssimple autosps spec_bin
+
+# The common object files required by the programs
+# We wrap them in addprefix to place them inside the build directory
+COMMON_NAMES = sps_vars.o sps_utils.o compsp.o csp_gen.o ssp_gen.o \
+    getmags.o locate.o funcint.o sps_setup.o pz_convol.o \
+    get_tuniv.o intsfwght.o imf.o imf_weight.o add_dust.o \
+    getspec.o sbf.o add_bs.o mod_hb.o add_remnants.o getindx.o \
+    smoothspec.o mod_gb.o add_nebular.o add_xrb.o write_isochrone.o \
+    sfhstat.o linterp.o tsum.o add_agb_dust.o linterparr.o \
+    ztinterp.o vacairconv.o igm_absorb.o get_lumdist.o attn_curve.o \
+    sfh_weight.o sfhlimit.o sfhinfo.o setup_tabular_sfh.o agn_dust.o
+
+COMMON_OBJS = $(addprefix $(BUILD_DIR)/, $(COMMON_NAMES))
+
+# ===================================
+# Rules
+# ===================================
+
+.PHONY: all clean test
+
+all: $(PROGS)
+
+# --- Compilation Rules ---
+
+# Ensure build directory exists before compiling
+$(BUILD_DIR):
+	@mkdir -p $(BUILD_DIR)
+
+# Pattern rule: Compile any .f90 found in VPATH to .o in BUILD_DIR
+$(BUILD_DIR)/%.o: %.f90 | $(BUILD_DIR)
+	$(FC) $(FCFLAGS) -c $< -o $@
+
+# Specific dependencies to enforce compilation order
+
+# sps_utils.o specifically depends on sps_vars.o
+$(BUILD_DIR)/sps_utils.o: $(BUILD_DIR)/sps_vars.o
+
+# All other common objects depend on both vars and utils.
+REST_OF_COMMON = $(filter-out $(BUILD_DIR)/sps_vars.o $(BUILD_DIR)/sps_utils.o, $(COMMON_OBJS))
+
+$(REST_OF_COMMON): $(BUILD_DIR)/sps_vars.o $(BUILD_DIR)/sps_utils.o
+
+# Main program objects also wait for modules
+$(BUILD_DIR)/simple.o $(BUILD_DIR)/lesssimple.o $(BUILD_DIR)/autosps.o $(BUILD_DIR)/spec_bin.o: $(BUILD_DIR)/sps_vars.o $(BUILD_DIR)/sps_utils.o
+
+# Dependencies for test objects
+$(BUILD_DIR)/generate_test_data.o: $(BUILD_DIR)/sps_vars.o $(BUILD_DIR)/sps_utils.o
+$(BUILD_DIR)/test_runner.o: $(BUILD_DIR)/sps_vars.o $(BUILD_DIR)/sps_utils.o
+
+# --- Linking Rules ---
+
+autosps: $(BUILD_DIR)/autosps.o $(COMMON_OBJS)
+	$(FC) $(FCFLAGS) -o $@ $^
+
+simple: $(BUILD_DIR)/simple.o $(COMMON_OBJS)
+	$(FC) $(FCFLAGS) -o $@ $^
+
+lesssimple: $(BUILD_DIR)/lesssimple.o $(COMMON_OBJS)
+	$(FC) $(FCFLAGS) -o $@ $^
+
+spec_bin: $(BUILD_DIR)/spec_bin.o $(BUILD_DIR)/sps_vars.o
+	$(FC) $(FCFLAGS) -o $@ $^
+
+# --- Test Targets ---
+
+generate_test_data: $(BUILD_DIR)/generate_test_data.o $(COMMON_OBJS)
+	$(FC) $(FCFLAGS) -o $@ $^
+
+test_runner: $(BUILD_DIR)/test_runner.o $(COMMON_OBJS)
+	$(FC) $(FCFLAGS) -o $@ $^
+
+test: test_runner
+
+# --- Utilities ---
+
+clean:
+	rm -rf $(BUILD_DIR) $(PROGS) generate_test_data test_runner
+

README.md

@@ -1,23 +1,24 @@
 FSPS: Flexible Stellar Population Synthesis
 =====
-version 3.2
+![Version Badge](https://img.shields.io/badge/version-v3.2-blue)
 
 References
 ---------
 When using this code please cite the following papers:
- * Conroy, Gunn, & White 2009, ApJ, 699, 486
- * Conroy & Gunn 2010, ApJ, 712, 833
+ * [Conroy, Gunn, & White 2009, ApJ, 699, 486](https://ui.adsabs.harvard.edu/abs/2009ApJ...699..486C)
+ * [Conroy & Gunn 2010, ApJ, 712, 833](https://ui.adsabs.harvard.edu/abs/2010ApJ...712..833C)
 
 Installation
 ----------
-If you have git installed, FSPS can be obtained with the following commands:
-```
+If you have Git installed, FSPS can be obtained with the following commands:
+
+```sh
 cd /path/to/desired/location/
 git clone https://github.com/cconroy20/fsps
 ```
-Otherwise download a gzipped tarball from [here](https://github.com/cconroy20/fsps/releases). Then follow the instructions at [doc/INSTALL](doc/INSTALL).
+Otherwise download a gzipped tarball from [here](https://github.com/cconroy20/fsps/releases). Then follow the instructions at [`doc/INSTALL`](doc/INSTALL).
 
-You should not need to update the git repository until an update is announced (which is why you need to be on the mailing list - see [doc/INSTALL](doc/INSTALL)).  If you've obtained FSPS using git then when an update is announced you will need to simply type ``cd $SPS_HOME; git pull`` and then recompile.  If you have made your own edits to the FSPS files, git will attempt to gracefully merge your local version with the repository version.
+You should not need to update the Git repository until an update is announced (which is why you need to be on the mailing list - see [`doc/INSTALL`](doc/INSTALL)).  If you've obtained FSPS using Git then when an update is announced you will need to simply type `cd $SPS_HOME; git pull` and then recompile (just type `make`).  If you have made your own edits to the FSPS files, Git will attempt to gracefully merge your local version with the repository version.
 
 Documentation
 ------
@@ -28,46 +29,46 @@ Contents
 Below is a brief description of the contents of the directories in the
 fsps root directory:
 
- * `ISOCHRONES`: Contains the isochrone tables for the BaSTI and Padova
+ * [`ISOCHRONES`](ISOCHRONES): Contains the isochrone tables for the BaSTI and Padova
 isochrone sets.  The Geneva isochrones have been pasted onto the BaSTI
 and Padova tables for high masses (M>70Msun), and the low-mass Lyon
 models have been pasted on at low masses.  You should not edit these
 files unless you know what you're doing.
 
- * `OUTPUTS`: Contains the outputs of a few example calls of the routines
+ * [`OUTPUTS`](OUTPUTS): Contains the outputs of a few example calls of the routines
 autosps and simple.  You may wish to use this directory for all
 outputs of the fsps routines.
 
- * `SPECTRA`: Contains the spectral libraries, the spectrum of an A0V star
+ * [`SPECTRA`](SPECTRA): Contains the spectral libraries, the spectrum of an A0V star
 used to set the Vega magnitude zero points, and a spectrum of the Sun.
 The BaSeL spectra (based on the Kurucz models) are in binary format,
 primarily to make the read in time faster and to decrease the size of
 the fsps download.  The Hot_spectra directory contain the libraries
 for O stars, WR stars, and post-AGB stars, from Smith et al. 2002 and
 Rauch 2003, respectively.
 
- * `data`: Contains files that define the set of filters and indices used
+ * `build`: Contains the compiled object files (`.o`) and Fortran modules (`.mod`).
+This directory is automatically created when you run `make`.
+
+ * [`data`](data): Contains files that define the set of filters and indices used
 in FSPS and the tabulated imfs and sfhs if those options are set.  The
 files in this directory are readily user editable.
 
- * `doc`: Contains the manual, revision history, and installation
+ * [`doc`](doc): Contains the manual, revision history, and installation
 instructions.
 
-* `dust`: Contains the dust attenuation curves for the Witt & Gordon
+* [`dust`](dust): Contains the dust attenuation curves for the Witt & Gordon
 (2000) dust model and the dust emission spectra from the Draine & Li
 2007 grain model.  Also contains the circumstellar dust models from 
 Villaume et al. 2015 and the AGN dusty torus models of Nenkova et al. 2008.
 
-* `nebular`: Contains the Cloudy lookup tables for nebular emission 
+* [`nebular`](nebular): Contains the Cloudy lookup tables for nebular emission 
 (both continuum and line emission) computed by Nell Byler.
 
-* `pro`: Contains IDL files for reading in the .mag, .indx, and .spec
+* [`pro`](pro): Contains IDL files for reading in the .mag, .indx, and .spec
 output files
 
-* `src`: Contains the source files and routines from Numerical Recipes.
-
-
-
-
-
+* [`src`](src): Contains the source files and routines from Numerical Recipes.
 
+* [`tests`](tests): Contains the regression test suite and scripts for generating
+reference comparison data.

doc/INSTALL

@@ -1,18 +1,22 @@
 SETUP INSTRUCTIONS
 
-1.   edit your .cshrc (or .bashrc) file to something like:
-     	  setenv SPS_HOME /home/user/fsps/
-	  (this should point to the directory containing the src directory)
+1.  Edit your .cshrc (or .bashrc/zshrc) file to set the SPS_HOME variable:
+            export SPS_HOME="/home/user/fsps/"
+       (this must point to the root directory containing the src/ directory)
 
-2.  edit the makefile in the src directory so that it is using your
-    fortran compiler one should then be able to compile everything by
-    simply typing "make"
+2.  Compile the code. The Makefile is located in the root directory.
+    By default, it uses gfortran. You can compile by simply typing:
+            make
+
+    If you wish to use a different compiler (e.g., ifort), you can specify it
+    on the command line without editing the Makefile:
+            make FC=ifort
 
 3.  email cconroy@cfa.harvard.edu so that I can keep you posted on updates.  
       -> this step is actually important!  Every code has bugs.  If I
-	 don't know that you're using this code, I can't tell you
-	 that I found a catastrophic bug that invalidates all of your
-	 results.
+      don't know that you're using this code, I can't tell you
+      that I found a catastrophic bug that invalidates all of your
+      results.
 
 4.  please email me if have any problems or find any bugs.
 
@@ -23,4 +27,10 @@ NOTES:
 1.  It has been reported that the code crashes if compiled with
     earlier versions of gfortran (specifically v4.2.1).  The code has
     been tested and compiles sucessfully with gfortran v4.4 and later.
-    (FYI, I currently compile FSPS with gfortran v6.4.0).
+    (FYI, I currently compile FSPS with gfortran v6.4.0).
+
+2.  As of 2026, the code allows for runtime selection of isochrones and
+    spectral libraries. You do NOT need to edit sps_vars.f90 and 
+    recompile to switch between MIST, Padova, MILES, BaSeL, etc.
+    These options can now be passed directly to the setup routines or 
+    selected interactively in the `autosps` driver.

doc/REVISION_HISTORY

@@ -149,4 +149,18 @@
 
 04/2/21
  - Release of v3.2
- - added THEMIS dust emission model
+ - added THEMIS dust emission model
+
+01/28/26
+ - Major modernization of the codebase and build system.
+ - Key Feature: Isochrone and spectral libraries can now be selected at 
+   runtime. You no longer need to edit `sps_vars.f90` and recompile to switch 
+   between MIST, Padova, MILES, BaSeL, etc.
+ - Implemented dynamic memory allocation throughout the driver programs 
+   (`simple`, `lesssimple`, `autosps`), removing compile-time static array limits.
+ - `autosps` is now interactive and will prompt the user to select their desired
+   libraries at runtime.
+ - The `Makefile` has been moved to the root directory and now uses an 
+   out-of-source build system (all artifacts are output to `build/`).
+ - Fixed legacy compiler warnings regarding FORMAT strings.
+ - Updated CI/CD infrastructure for regression testing.