scivision / fortran2018-examples

Fortran 2018 standard examples with broad applications

Fortran 2018 Examples

Standalone examples of Fortran 2018 and 2023 standard features. Popular, free-to-use Fortran compilers (GCC, Intel oneAPI, NVIDIA, Cray, IBM OpenXL, AOCC, Flang) and paid compilers such as NAG support all or many Fortran 2008 and 2018 standards.

Some standard Fortran features are so distinctive that we've put examples in separate repos:

• C / C++ interface to/from Fortran
• Fortran submodule
• Fortran coarray: modern Fortran is the only major compiled language standard with intrinsic massively parallel arrays. Also contains MPI examples.
• do concurrent, OpenMP, OpenACC: parallel execution with Fortran directives and native syntax.

The examples are built with CMake:

cmake --workflow --preset default

or to do each step manually:

cmake -B build
cmake --build build
ctest --test-dir build -V

Programs

The standalone examples are organized under test/ directory, including:

• array: Array math in modern CMake and Fortran
• Git traceability
• namelist: Fortran 90 / 2003 Namelist parsing -- native text config files for Fortran
• io: modern Fortran File I/O including resolving absolute path
• real: Numerous examples dealing with practical features of real floating point numbers, including sentinel NaN and polymorphism.
• character: String handling is easy and performant in modern Fortran.
• standard: advanced features that can be done with Fortran standard coding
• submodule: Fortran 2008 and CMake ≥ 3.12 enable even better large program architecture with submodule
• system: system (hardware) functionality accessible via Fortran

Companion libraries and examples

• object-oriented Fortran HDF5 interface: h5fortran
• object-oriented Fortran NetCDF4 interface: nc4fortran
• sparse-matrix examples in Fortran

Resources

Fortran standards

• Fortran I 1956 manual

• Fortran II 1958 manual

• Fortran 66 standard

• Fortran 77 language reference

• Fortran 77

• Fortran 90 / 95 manual

• Fortran 2003

• Fortran 2008

• Fortran 2018

• Fortran 2023

Books

• Modern Fortran Explained: Incorporating Fortran 2018. Metcalf, Reid, Cohen. 5th Ed, Nov 2018. ISBN: 978-0198811886.
• Modern Fortran: Building Efficient Parallel Applications. Milan Curcic. Feb. 2019. ISBN: 978-1617295287.

Compiler User Guides

• Cray Fortran
• Flang Wiki
• GNU Fortran docs
• IBM OpenXL
• Intel Fortran
• NAG Fortran
• NVIDIA HPC SDK

Surveys

• 2018 modern Fortran user survey

fortran2018-examples's Issues

add fortran-tutorial tag

Could you add the tag fortran-tutorial to your project? If all relevant repos add this tag it will make such material easier to find on GitHub. Currently topics such javascript-tutorial and python-tutorial have many entries.

cmake errors

ian@ian-Aspire-One-753:$ cd fortran2018*
ian@ian-Aspire-One-753:/fortran2018examples$ ls
abi_check CMakeCache.txt _deps namelist real
array CMakeFiles fortran2018-examples openmp standard
benchmarks compile git overloading submodule
block contiguous io pointer system
character debug maximum random
ian@ian-Aspire-One-753:~/fortran2018examples$ cmake fortran2018-examples
CMake Error: Could not find CMAKE_ROOT !!!
CMake has most likely not been installed correctly.
Modules directory not found in
/usr/local/share/cmake-3.16
CMake Error: Error executing cmake::LoadCache(). Aborting.

ian@ian-Aspire-One-753:~/fortran2018examples$ sudo cmake fortran2018-examples
fatal: not a git repository (or any of the parent directories): .git
CMake Error at git/CMakeLists.txt:14 (string):
string sub-command SUBSTRING requires four arguments.

fatal: not a git repository (or any of the parent directories): .git
CMake Error at git/CMakeLists.txt:18 (string):
string sub-command SUBSTRING requires four arguments.

fatal: not a git repository (or any of the parent directories): .git
-- Fortran2018Examples git revision: git_branch: git_porcelain: .true.
-- CMake at least through 3.20.1 and Make have a bug with this Fortran Syntax. CMake + Ninja works OK.

• Openmp, tests using OpenMP

-- Configuring incomplete, errors occurred!
See also "/home/ian/fortran2018examples/CMakeFiles/CMakeOutput.log".
See also "/home/ian/fortran2018examples/CMakeFiles/CMakeError.log".

fortran program svd_example ! Declare variables integer, parameter :: m = 4, n = 3, lda = 4, ldu = 4, ldvt = 3 integer :: i, j, info real(kind=8) :: a(lda,n), s(n), u(ldu,m), vt(ldvt,n), superb(min(m,n)-1) ! Initialize matrix A with some random values do j=1,n do i=1,m a(i,j) = dble((i-1) + (j-1)*m) end do end do ! Compute the SVD of matrix A using LAPACK routine DGESVD call dgesvd('A', 'A', m, n, a, lda, s, u, ldu, vt, ldvt, superb, info) ! Print the results: matrices U and Vt and vector S. write(*,'(a)') 'Matrix U:' do i=1,m write(*,'(4f8.2)') (u(i,j),j=1,min(m,n)) end do write(*,*) write(*,'(a)') 'Vector S:' write(*,'(3f8.2)') (s(j),j=1,min(m,n)) write(*,*) write(*,'(a)') 'Matrix Vt:' do i=1,min(m,n) write(*,'(3f8.2,a,f8.2)') (vt(i,j),' ',char(10),superb(i)) end do end program svd_example

MAINT: keeping test counts same cmake/meson/ compilers / os

The test counts should be identical across compilers, meson/cmake, and operating system.
This takes a little extra maintenance and is an ongoing task.

libISO

I do use Ubuntu 18.10. I was only successful with cmake and 'make test' when I changed
/usr/lib/x86_64-linux-gnu/cmake/opencoarrays/OpenCoarraysTargets-none.cmake
at line 42 and 46 from 'libcISO_Fortran_binding.a' to 'libISO_Fortran_binding.so.2.1.0'
Thank you for the stuff!