Hi, Thanks for the help with Makefile for multiple files in PETSc, I've also found a way that works for me, simply add these two libs: LIBSCOMP = -I/gpfs_irving/irving/xji/petsc-3.0.0-p5/linux-gnu-c-debug/include -I/gpfs_irving/irving/xji/petsc-3.0.0-p5/include -I/usr/X11R6/include LIBSLINK = -Wl,-rpath,/gpfs_irving/irving/xji/petsc-3.0.0-p5/linux-gnu-c-debug/lib -L/gpfs_irving/irving/xji/petsc-3.0.0-p5/linux-gnu-c-debug/lib -lpetscts -lpetscsnes -lpetscksp -lpetscdm -lpetscmat -lpetscvec -lpetsc -L/usr/X11R6/lib -lX11 -llapack -lblas -L/usr/local/intel/mpich-1.2.7p1/linux86/9.1/lib -ldl -lmpich -lpthread -lrt -L/usr/local/intel/cc/9.1.045/lib -L/usr/lib/gcc/i386-redhat-linux/3.4.6 -limf -lipgo -lgcc_s -lirc -lirc_s -lmpichf90 -L/usr/local/intel/fc/9.1.040/lib -lifport -lifcore -lm -lm -ldl -lmpich -lpthread -lrt -limf -lipgo -lgcc_s -lirc -lirc_s -ldl LIBSCOMP is for compiling .F90 files into .o and LIBSLINK is for linking .o files into single executable. I did not use "include ${PETSC_DIR}/conf/base" Now I came up with this new problem, I could not find the way to let petsc mat store double precision values. I used double precision value in MatSetValue() but the MatView showed the stored data to be single precision. I've also tried to recompile petsc as: ./config/configure.py --with-precision=double which didnot work for me. Thanks very much. Xiaoyin Ji ---------------------------------------------- Xiaoyin Ji Graduate Student Department of Materials Science and Engineering North Carolina State University