MPI_Abi_set_fortran_booleans(3)

💖 MPI_Abi_set_fortran_booleans — bestie edition 💖

okay so welcome to the MPI manual, babe. today's hyperfixation is MPI_Abi_set_fortran_booleans(3) and honestly? she's a niche queen and we love her for it. 💅

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✨ NAME ✨

MPI_Abi_set_fortran_booleans — sets the Fortran logical type size and the values that count as .TRUE. and .FALSE. 🎀

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🌸 SYNOPSIS 🌸

int MPI_Abi_set_fortran_booleans(int logical_size, void *logical_true,
       void *logical_false)

like. she takes three things and she does her little thing. periodt. ✨

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🦋 INPUT PARAMETERS 🦋

• logical_size — the size of a Fortran LOGICAL, in bytes (it's an integer, bestie)
• logical_true — the Fortran literal value .TRUE. (a logical, obviously)
• logical_false — the Fortran literal value .FALSE. (yes, this one too)

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🧚 THREAD AND INTERRUPT SAFETY 🧚

okay so the good news first: this routine is thread-safe. that means multiple threads can run it at the same time and you do not need to bring your own thread locks, no cap. 🫶

the not-so-good news: she is not interrupt safe. typically this is because of memory allocation routines like malloc, or other non-MPICH runtime routines that are themselves not interrupt-safe. so like… interrupt at your own risk, babe. 😭

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💜 NOTES FOR FORTRAN 💜

• every MPI routine in Fortran (except for the iconic duo MPI_WTIME and MPI_WTICK) gets one extra argument at the end of the argument list: ierr. ierr is an integer and it means exactly the same thing as the return value of the routine in C. iykyk. 💅
• in Fortran, MPI routines are subroutines, and you invoke them with the call statement. yes, call. we stan.
• all MPI objects (like MPI_Datatype, MPI_Comm) are of type INTEGER in Fortran. that's just the vibe.

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⭐ ERRORS ⭐

so basically every MPI routine (except MPI_Wtime and MPI_Wtick) hands back an error value — C routines return it as the value of the function, and Fortran routines put it in that last argument. before the value comes back, the current MPI error handler gets called. 📞

by default, that error handler aborts the entire MPI job. like, the whole thing. gone. 💀

the error handler can be swapped out with:

• MPI_Comm_set_errhandler (for communicators)
• MPI_File_set_errhandler (for files)
• MPI_Win_set_errhandler (for RMA windows)

the MPI-1 routine MPI_Errhandler_set may also be used, but heads up — its use is deprecated. 🙈

and if you're the type who wants error values returned instead of the whole program going poof, there's the predefined error handler MPI_ERRORS_RETURN. slay. 💅

also important, and I need you to hear me on this: MPI does not guarantee that an MPI program can keep going after an error. however, MPI implementations will attempt to continue whenever possible. so… she'll try her best, bestie. 🥺

the error codes:

• MPI_SUCCESS — no error, everything ate, the routine completed successfully. 👑
• MPI_ERR_ARG — invalid argument. some argument is invalid and it's not identified by a specific error class (e.g., MPI_ERR_RANK). 🙃
• MPI_ERR_OTHER — other error. use MPI_Error_string to get more info about this error code. she's vague on purpose. 😭

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and that's the whole page, bestie!! now go forth and set those Fortran booleans, main character energy only. 🌈✨

this was the MPI manual manpage for MPI_Abi_set_fortran_booleans, dated 4/10/2026 💖 mwah, love u, bye 🫶