Modern Fortran Refactoring of MUDPACK SP Package (SPAG v8, F90)

This repository provides a clean Fortran 90 refactoring of the SP (Separable) package from the original MUDPACK library, developed by the National Center for Atmospheric Research (NCAR). The goal is to preserve the numerical behavior of the SP routines while modernizing code structure, improving readability, and ensuring compatibility with contemporary Fortran compilers.

About MUDPACK SP

• MUDPACK is a collection of Fortran subroutines for solving elliptic partial differential equations using multigrid techniques on rectangular grids.
• The SP package targets separable, constant-coefficient elliptic problems in 1D, 2D, and 3D Cartesian domains with homogeneous boundary conditions.

Refactoring Highlights

• Fully converted to Fortran 90 with MODULEs and explicit interfaces
• Modern naming conventions and consistent formatting
• Modular code layout for easier maintenance and extension
• No changes to underlying algorithms; numerical results are identical to the original

Repository Contents

src/            # Fortran 90 source files for SP routines
tests/          # Not Ported yet
build/          # Build scripts and Makefile
README.md       # This file

Prerequisites

• A Fortran 90–compatible compiler (e.g., gfortran, ifort)
• GNU Make (or compatible build tool)

Building

mkdir -p build && cd build
cmake ..
make

Usage

After building, link the compiled library into your application:

use mudpack_sp
! ... call solver routines as documented in the module interfaces

Testing

Run the provided test suite to verify correctness:

cd build
make test

Importing MUDPACK into Your Project

Using FetchContent (CMake 3.11+)

MUDPACK can be easily integrated into your CMake project using FetchContent:

cmake_minimum_required(VERSION 3.11)
project(YourProject)

include(FetchContent)

# Declare the dependency
FetchContent_Declare(mudpack_sp
    GIT_REPOSITORY https://github.com/trifwn/mudpack_sp
    GIT_TAG main  # or specify a version tag/commit
    TLS_VERIFY true
)

# Option 1: Using FetchContent_MakeAvailable (CMake 3.14+)
FetchContent_MakeAvailable(mudpack_sp)

# Option 2: Manual approach (CMake 3.11+)
# FetchContent_GetProperties(mudpack_sp)
# if(NOT mudpack_sp_POPULATED)
#     FetchContent_Populate(mudpack_sp)
#     add_subdirectory(${mudpack_sp_SOURCE_DIR} ${mudpack_sp_BINARY_DIR} EXCLUDE_FROM_ALL)
# endif()

# Your target
add_executable(your_program main.cpp)

# Link against MUDPACK
target_link_libraries(your_program PRIVATE mudpack_sp)

Using find_package (for installed MUDPACK)

If MUDPACK is installed on your system:

cmake_minimum_required(VERSION 3.10)
project(YourProject)

find_package(mudpack_sp REQUIRED)

add_executable(your_program main.cpp)
target_link_libraries(your_program PRIVATE mudpack::mudpack_sp)

Requirements

• CMake 3.11+ (for FetchContent)
• A Fortran compiler

License

This refactored code is released under the MIT License.