[petsc-dev] Fwd: MatSetValues with v=0

[Eric Chamberland]

On 04/16/2014 06:00 PM, Barry Smith wrote:
>    Removed in barry/rm-null-values-to-matsetvalues and next

doh!  ;-)

Ok, I have done it with my own vector of zeros...

Now I noticed another thing while measuring performances (notice: I used 
a PETSc compiled with debugging=yes... please don't flame me...):

The first assembly for a 549252 square matrix takes me 4.505s but if i 
sort the indices passed to MAT_SET_VALUES (which I can do since I add 
only zeros) it takes only 1.655s!!!!!  Sorting the indices costs me only 
0.4s...

Is this a normal behavior?  If so, it means we shall number our DOF in a 
way that the elementary matrices have DOF # that are mostly sorted while 
doing the "standard" assembly?

Thanks,

Eric