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Questions tagged [fortran-coarrays]

This tag is for questions specifically relating to the coarray (a partitioned global address space model) feature introduced in Fortran 2008. The tag should not be used simply because a problem example uses coarrays. In addition, the general Fortran tag should be added and no revision-specific Fortran tag prior to Fortran 2008 should feature.

25 questions
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Passing a coarray subarray to a function gives a wrong part of the array

I'm attempting to understand how to pass a slice of a multidimensional co-array to a function. I would like to use a function like this: function get_int_vec(vec_int_2get, rank) result(ret_val) implicit none integer, dimension(:),…
Sparonuz
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Coarrays disabled use -fcoarrays=?

I'm trying to run a Fortran code that follows the example for the book: Curcic, M. 2020. Modern Fortran: Building Efficient Parallel Applications. Although I get the following error when I run it and I'm not experienced enough to understand what…
Stackbeans
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Why does coarray with allocatable component creates segmentation faults when accessed from different image?

I want to use the fortran coarray feature to have different size arrays on different images. Following the 2008/2018 standard, this should be possible by using a derived type containing an allocatable. I am using gfortran 8.2.0 with opencoarrays…
Frenz
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When and where are writes to coarrays visible in Fortran?

I have this program, and would expect this to print 1 2 when run with 2 images. However, it prints 1 1 on one image, and 1 2 on the other. program main implicit none double precision, allocatable :: a[:] allocate(a[*]) a =…
asdfldsfdfjjfddjf
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Is/Will there be a way to perform Fortran Coarray calls asynchronously?

I've been falling in love with the ease-of-use of Fortran's Coarrays framework, because of how clean it is compared to lower level APIs like MPI. But one thing I haven't been able to tease out is whether there is a way to know how to explicitly tell…
Edward Yang
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How to mix Coarray and MPI code in Fortran

I would like to combine Fortran coarray with MPI inside my code. I plan to use third party softwave(HYPRE), which used MPI, for linear system solvers. For the rest of my work, I want to use the Fortran coarray (OpenCoarrays). I've already searched…
Tung Dang
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Application throws segmentation fault after some time on calling a procedure (containing local coarrays) in a loop

I am trying to call a subroutine in a loop. This subroutine has a local coarray. Following is the code that I am using: ! Test local coarray in procedure called in a loop. ! program main use, intrinsic :: iso_fortran_env, only : input_unit,…
Ombrophile
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calling a Coarray Fortran shared library from Python

I am trying to understand how a Coarray Fortran DLL can be possibly called from Python. Consider the following sample Fortran module file example_mod.f90 which is to be called from Python later: module example_mod use iso_c_binding implicit…
Scientist
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Coarray derived type of allocatable vector of allocatable character components

Consider the following code that attempts to create a coarray derived type containing an array of variable-length allocatable character types. program testCoarrayJaggedArray implicit none integer :: i type ::…
Scientist
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Coarray deadlock in do-cycle-exit

A strange phenomenon occurs in the following Coarray code program strange implicit none integer :: counter = 0 logical :: co_missionAccomplished[*] co_missionAccomplished = .false. sync all do if (this_image()==1) then counter = counter+1 …
Scientist
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Only one image in Fortran Coarrays in gfortran

I'm using gfortran compiler and trying to work on parallel programming without MPI. Even though, I spent too much time on reading about Fortran, gfortran, parallel programming, I couldn't do anything to use different processors at the same time. My…
Lito
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Coarray Fortran segfaults when passing distributed argument

I am getting a segfault in C = C + matmul(A(:, 1 + (l - 1) * n / p: l * n / p), B(:,:)[l]) using gfortran + mpich, with n = 4000, p = 2. Is it not allowed to pass slices of distributed arrays into functions? When copying out B(:,:)[l], it is super…
asdfldsfdfjjfddjf
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Fortran segmentation fault when deallocating a coarray component of a derived type (bug?)

I get a segfault when trying to deallocate a coarray component of a derived type. This happens after I assign one instance of the type to another. The minimal example is as follows: program mytest implicit none type notmytype real,…
water
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Run only part of fortran coarray code parallel rest serial

I have a main program that has subroutine written using coarrays. The problem is that while running the code it treats the entire code (main + subroutine) as parallel code and runs it on all specified processors. For eg., the Below program prints…
codegeek
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coarray fortran array doesn't get updated

I'm just learning to use coarry with Fortran. I have a very simple program. I have an array of length 9 that I want to distribute over 3 processes, do some calculations, and merge them back to a single array (basic MPI_scatter/MPI_gather like…
Eular
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