petsc-3.11.4 2019-09-28
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Gets an environmental variable, broadcasts to all processors in communicator from first.


PetscErrorCode  PetscOptionsGetenv(MPI_Comm comm,const char name[],char env[],size_t len,PetscBool  *flag)
Collective on MPI_Comm

Input Parameters

comm - communicator to share variable
name - name of environmental variable
len - amount of space allocated to hold variable

Output Parameters

flag - if not NULL tells if variable found or not
env - value of variable


You can also "set" the environmental variable by setting the options database value -name "stringvalue" (with name in lower case). If name begins with PETSC_ this is discarded before checking the database. For example, PETSC_VIEWER_SOCKET_PORT would be given as -viewer_socket_port 9000

If comm does not contain the 0th process in the MPIEXEC it is likely on many systems that the environmental variable will not be set unless you put it in a universal location like a .chsrc file




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