https://community.intel.com/t5/Intel-MPI-Library/MPI-size-0-while-everything-else-seems-to-work/m-p/1745157#M12273 <P>Hi,</P><P>I posted this question a few days ago but supplied little background data.</P><P>I went ifort to ifx with just&nbsp; one or two changes in the bat files for compile, link and run.</P><P>Everything seems to work as before but at runtime I saw that size became undefined although</P><P>ierr=0 when MPI_COMM_size and MPI_COMM_rank were called. The main routine, cl.bat (compile+link) and r1.bat (run) are attached.&nbsp;</P><P>Grateful for a quick answer!</P><P>Best regards</P><P>Sanders</P> Tue, 21 Apr 2026 06:29:46 GMT Sanders1 2026-04-21T06:29:46Z https://community.intel.com/t5/Intel-MPI-Library/MPI-size-0-while-everything-else-seems-to-work/m-p/1745157#M12273 <P>Hi,</P><P>I posted this question a few days ago but supplied little background data.</P><P>I went ifort to ifx with just&nbsp; one or two changes in the bat files for compile, link and run.</P><P>Everything seems to work as before but at runtime I saw that size became undefined although</P><P>ierr=0 when MPI_COMM_size and MPI_COMM_rank were called. The main routine, cl.bat (compile+link) and r1.bat (run) are attached.&nbsp;</P><P>Grateful for a quick answer!</P><P>Best regards</P><P>Sanders</P> Tue, 21 Apr 2026 06:29:46 GMT https://community.intel.com/t5/Intel-MPI-Library/MPI-size-0-while-everything-else-seems-to-work/m-p/1745157#M12273 Sanders1 2026-04-21T06:29:46Z