make PETSC_ARCH=arch rosenbrock1which compiles a debugging or optimized version of the example and automatically link the appropriate libraries. The architecture, arch, is one of solaris, rs6000, IRIX, hpux, etc. Note that when using command line options with make (as illustrated above), one must not place spaces on either side of the ``='' signs. The variable PETSC_ARCH can also be set as an environmental variable.