Compiling with or without petsc

[Laslo Tibor Diosady]

Hi,

I'm trying to create a distribution  which can be built both with and 
without petsc. The idea behind this is that when only running uni-processor cases 
typically petsc will not be needed so that users do not need a copy of 
petsc on their machine. I was wondering if  there is an easy way to detect 
the presence of petsc on your local machine and if petsc exists have 
a flag set which can be used in the makefile to comile with petsc. Also 
would it be possible to find the top petsc directory and specity the 
environment variables $PETSC_DIR and $PETSC_ARCH so that this does not 
need to be done manually by the user.

Any help in this area would be greatly appreciated.

Thanks,

Laslo