[petsc-users] Changing the options in the makefile

Hi, I have a modified makefile originally given to me by the PETSc team. It worked well but now I want to change some of the options of the compiler, like using -O3 or -ipo etc instead of -O. I tried to add -O3 in and the compiling command becomes: /opt/openmpi-1.4.1/bin/mpif90 -O3 -c -g -r8 -save -w90 -w -w95 -O -I/home/wtay/Lib/petsc-3.1-p5/include .... So now there's -O3 and -O. How can I change it to only -O3 or -ipo? I have attached the makefile too. Thank you very much Yours sincerely, TAY wee-beng