[petsc-users] using fieldsplit for matrix assembled using aij

Hello, I have a matrix assembled in interlaced format. I am not able to follow how to use fieldsplit. Is there a good example to show how to do this. My variable are in this format [ {u1,v1,p1}, {u2,v2,p2}, ....,{un,vn,pn}], where n is the number of grid points and u,v,p are the velocity and pressure components. The matrix is assembled as [ uu11 uv11 up11 uu12 uv12 up12 ...... vu11 vv11 vp11 vu12 vv12 vp12 ....... pu11 pv11 pp11 pu12 pv12 pp12 ...... uu21 uv21 up21 uu22 uv22 up22 ...... vu21 vv21 vp21 vu22 vv22 vp22 ....... pu21 pv21 pp21 pu22 pv22 pp22 ...... . . ] I want to split u and v fields as one block and p field as another block. Any help would be appreciated. Raju.