Randy, Thanks for pointing out this problem. I was generating the wrong C stubs for arguments such as PetscViewerAndFormat, that is arguments that are C structs but treated as FortranAddr in Fortran because the C struct is too complex to be directly represented in Fortran.
This is fixed in https://urldefense.us/v3/__https://gitlab.com/petsc/petsc/-/merge_requests/8563__;!!G_uCfscf7eWS!ZJ2LzM36kh8gWYIb5xKHC93lz7AjKZEaJaTVb7JIHJ2VZQ6psyGi7AKwT6E6zu-TflxcNJEnP0zppaV27SmvFCo$ and should allow you to do what you previously had done. In the MR you will see I have modified ex2f.F to do essentially what your test code is doing. Barry > On Jun 23, 2025, at 2:46 PM, Randall Mackie <rlmackie...@gmail.com> wrote: > > In previous versions of PETSc we use to be able to call > KSPMonitorTrueResidual from within our custom KSPMonitor, using an approach > that is now commented out in the example found at > https://urldefense.us/v3/__https://petsc.org/release/src/ksp/ksp/tutorials/ex2f.F90.html__;!!G_uCfscf7eWS!ZJ2LzM36kh8gWYIb5xKHC93lz7AjKZEaJaTVb7JIHJ2VZQ6psyGi7AKwT6E6zu-TflxcNJEnP0zppaV2RnCwvyM$ > : > <https://urldefense.us/v3/__https://petsc.org/release/src/ksp/ksp/tutorials/ex2f.F90.html:__;!!G_uCfscf7eWS!ft8A0uxwHvTcBa5FwETVQYcImMgoOOueBeZT-7zP9jlaLFCDZ6ApRkBFUgoUzMRWCLbyU1FcxTgFoYMm8twVYS6KDQ$> > > ! > 214: <>! Cannot also use the default KSP > <https://urldefense.us/v3/__https://petsc.org/release/manualpages/KSP/KSP/__;!!G_uCfscf7eWS!ft8A0uxwHvTcBa5FwETVQYcImMgoOOueBeZT-7zP9jlaLFCDZ6ApRkBFUgoUzMRWCLbyU1FcxTgFoYMm8tx3EWnatA$> > monitor routine showing how it may be used from Fortran > 215: <>! since the Fortran compiler thinks the calling arguments are > different in the two cases > 216: <>! > 217: <>! PetscCallA > <https://urldefense.us/v3/__https://petsc.org/release/manualpages/Sys/PetscCallA/__;!!G_uCfscf7eWS!ft8A0uxwHvTcBa5FwETVQYcImMgoOOueBeZT-7zP9jlaLFCDZ6ApRkBFUgoUzMRWCLbyU1FcxTgFoYMm8tzA4vLgOQ$>(PetscViewerAndFormatCreate > > <https://urldefense.us/v3/__https://petsc.org/release/manualpages/Viewer/PetscViewerAndFormatCreate/__;!!G_uCfscf7eWS!ft8A0uxwHvTcBa5FwETVQYcImMgoOOueBeZT-7zP9jlaLFCDZ6ApRkBFUgoUzMRWCLbyU1FcxTgFoYMm8tykmBKBfg$>(PETSC_VIEWER_STDOUT_WORLD > > <https://urldefense.us/v3/__https://petsc.org/release/manualpages/Viewer/PETSC_VIEWER_STDOUT_WORLD/__;!!G_uCfscf7eWS!ft8A0uxwHvTcBa5FwETVQYcImMgoOOueBeZT-7zP9jlaLFCDZ6ApRkBFUgoUzMRWCLbyU1FcxTgFoYMm8tw_EZkgfA$>,PETSC_VIEWER_DEFAULT > > <https://urldefense.us/v3/__https://petsc.org/release/manualpages/Viewer/PetscViewerFormat/__;!!G_uCfscf7eWS!ft8A0uxwHvTcBa5FwETVQYcImMgoOOueBeZT-7zP9jlaLFCDZ6ApRkBFUgoUzMRWCLbyU1FcxTgFoYMm8tyZ_k-1Uw$>,vf,ierr)) > 218: <>! PetscCallA > <https://urldefense.us/v3/__https://petsc.org/release/manualpages/Sys/PetscCallA/__;!!G_uCfscf7eWS!ft8A0uxwHvTcBa5FwETVQYcImMgoOOueBeZT-7zP9jlaLFCDZ6ApRkBFUgoUzMRWCLbyU1FcxTgFoYMm8tzA4vLgOQ$>(KSPMonitorSet > > <https://urldefense.us/v3/__https://petsc.org/release/manualpages/KSP/KSPMonitorSet/__;!!G_uCfscf7eWS!ft8A0uxwHvTcBa5FwETVQYcImMgoOOueBeZT-7zP9jlaLFCDZ6ApRkBFUgoUzMRWCLbyU1FcxTgFoYMm8tx6T8FJsA$>(ksp,KSPMonitorResidual > > <https://urldefense.us/v3/__https://petsc.org/release/manualpages/KSP/KSPMonitorResidual/__;!!G_uCfscf7eWS!ft8A0uxwHvTcBa5FwETVQYcImMgoOOueBeZT-7zP9jlaLFCDZ6ApRkBFUgoUzMRWCLbyU1FcxTgFoYMm8txdiRZPSg$>,vf,PetscViewerAndFormatDestroy > > <https://urldefense.us/v3/__https://petsc.org/release/manualpages/Viewer/PetscViewerAndFormatDestroy/__;!!G_uCfscf7eWS!ft8A0uxwHvTcBa5FwETVQYcImMgoOOueBeZT-7zP9jlaLFCDZ6ApRkBFUgoUzMRWCLbyU1FcxTgFoYMm8tzN4PpBPA$>,ierr)) > > Instead, that example uses: > > 210: <> if (flg) then > 211: <> vzero = 0 > 212: <> PetscCallA > <https://urldefense.us/v3/__https://petsc.org/release/manualpages/Sys/PetscCallA/__;!!G_uCfscf7eWS!ft8A0uxwHvTcBa5FwETVQYcImMgoOOueBeZT-7zP9jlaLFCDZ6ApRkBFUgoUzMRWCLbyU1FcxTgFoYMm8tzA4vLgOQ$>(KSPMonitorSet > > <https://urldefense.us/v3/__https://petsc.org/release/manualpages/KSP/KSPMonitorSet/__;!!G_uCfscf7eWS!ft8A0uxwHvTcBa5FwETVQYcImMgoOOueBeZT-7zP9jlaLFCDZ6ApRkBFUgoUzMRWCLbyU1FcxTgFoYMm8tx6T8FJsA$>(ksp,MyKSPMonitor,vzero,PETSC_NULL_FUNCTION,ierr)) > 213: <>! > Regardless of which of these approaches I try, I cannot use > KSPMonitorTrueResidual in the MyKSPMonitor routine. > I get the following error: > > [0]PETSC ERROR: --------------------- Error Message > -------------------------------------------------------------- > [0]PETSC ERROR: Null argument, when expecting valid pointer > [0]PETSC ERROR: Null Pointer: Parameter # 4 > [0]PETSC ERROR: See > https://urldefense.us/v3/__https://petsc.org/release/faq/__;!!G_uCfscf7eWS!ZJ2LzM36kh8gWYIb5xKHC93lz7AjKZEaJaTVb7JIHJ2VZQ6psyGi7AKwT6E6zu-TflxcNJEnP0zppaV2eUazhhw$ > > <https://urldefense.us/v3/__https://petsc.org/release/faq/__;!!G_uCfscf7eWS!ft8A0uxwHvTcBa5FwETVQYcImMgoOOueBeZT-7zP9jlaLFCDZ6ApRkBFUgoUzMRWCLbyU1FcxTgFoYMm8tzxt44McA$> > for trouble shooting. > [0]PETSC ERROR: PETSc Release Version 3.23.3, May 30, 2025 > [0]PETSC ERROR: ./test with 2 MPI process(es) and PETSC_ARCH > linux-gfortran-complex-debug on rmackie-VirtualBox-2024 by rmackie Mon Jun 23 > 11:34:04 2025 > [0]PETSC ERROR: Configure options: --with-clean=1 --with-scalar-type=complex > --with-debugging=1 --with-fortran=1 --download-mpich=1 > [0]PETSC ERROR: #1 KSPMonitorTrueResidual() at > /home/rmackie/PETSc/petsc-3.23.3/src/ksp/ksp/interface/iterativ.c:400 > [0]PETSC ERROR: #2 test.F90:303 > > > I attach a slightly modified version of the example that demonstrates this > behavior. > > > Thanks for the help, > > Randy > > <test.F90> >
