<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML3.2 EN"> <HTML> <HEAD> <META NAME="GENERATOR" CONTENT="DOCTEXT"> <TITLE>MPI_Group_intersection</TITLE> </HEAD> <BODY BGCOLOR="FFFFFF"> <A NAME="MPI_Group_intersection"><H1>MPI_Group_intersection</H1></A> Produces a group as the intersection of two existing groups <H2>Synopsis</H2> <PRE> int MPI_Group_intersection(MPI_Group group1, MPI_Group group2, MPI_Group *newgroup) </PRE> <H2>Input Parameters</H2> <DL> <DT><B>group1 </B><DD>first group (handle) <DT><B>group2 </B><DD>second group (handle) </DL> <P> <H2>Output Parameter</H2> <DL><DT><B>newgroup </B> <DD> intersection group (handle) </DL> <P> <H2>Notes</H2> The output group contains those processes that are in both <TT>group1</TT> and <TT>group2</TT>. <P> <H2>Thread and Interrupt Safety</H2> <P> This routine is thread-safe. This means that this routine may be safely used by multiple threads without the need for any user-provided thread locks. However, the routine is not interrupt safe. Typically, this is due to the use of memory allocation routines such as <TT>malloc </TT>or other non-MPICH runtime routines that are themselves not interrupt-safe. <P> <H2>Notes for Fortran</H2> All MPI routines in Fortran (except for <TT>MPI_WTIME</TT> and <TT>MPI_WTICK</TT>) have an additional argument <TT>ierr</TT> at the end of the argument list. <TT>ierr </TT>is an integer and has the same meaning as the return value of the routine in C. In Fortran, MPI routines are subroutines, and are invoked with the <TT>call</TT> statement. <P> All MPI objects (e.g., <TT>MPI_Datatype</TT>, <TT>MPI_Comm</TT>) are of type <TT>INTEGER </TT>in Fortran. <P> <H2>Errors</H2> <P> All MPI routines (except <TT>MPI_Wtime</TT> and <TT>MPI_Wtick</TT>) return an error value; C routines as the value of the function and Fortran routines in the last argument. Before the value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job. The error handler may be changed with <TT>MPI_Comm_set_errhandler</TT> (for communicators), <TT>MPI_File_set_errhandler</TT> (for files), and <TT>MPI_Win_set_errhandler</TT> (for RMA windows). The MPI-1 routine <TT>MPI_Errhandler_set</TT> may be used but its use is deprecated. The predefined error handler <TT>MPI_ERRORS_RETURN</TT> may be used to cause error values to be returned. Note that MPI does <EM>not</EM> guarentee that an MPI program can continue past an error; however, MPI implementations will attempt to continue whenever possible. <P> <DL><DT><B>MPI_SUCCESS </B> <DD> No error; MPI routine completed successfully. </DL> <DL><DT><B>MPI_ERR_GROUP </B> <DD> Null or invalid group passed to function. </DL> <DL><DT><B>MPI_ERR_INTERN </B> <DD> This error is returned when some part of the MPICH implementation is unable to acquire memory. </DL> <P> <H2>See Also</H2> MPI_Group_free <BR><P><B>Location:</B>group_intersection.c<P> </BODY></HTML>