[petsc-users] a naive question about assembly

[huaibao zhang]

        
Hello,

I looked up the manual, but still felt  quite confused about why have to do 
assembly. Does it have to do with parallelization? Since all of the processors 
are loading the data at the same time, they need to a pause before one can use 
the whole vector? 

See a piece of code: 

                        for (int c=0;c<grid[gid].cellCount;++c) {
                                row=grid[gid].myOffset+c;
                                value=p;
                                
VecSetValues(soln_n,1,&row,&value,INSERT_VALUES);
                        }
                        VecAssemblyBegin(soln_n); VecAssemblyEnd(soln_n);


Thanks,
Paul