[petsc-users] How to use

[Jed Brown]

Sharp Stone <thronesf at gmail.com> writes:

> Hi all,
>
> In the ex19, specifically from Lines 581-587, about the "invert the system"
> part,
>
> 581:             /* invert the system:582:              [ dfu / du
> 0        0        0    ][yu] = [fu]583:              [     0    dfv /
> dv     0        0    ][yv]   [fv]584:              [ dfo / du dfo / dv
> dfo / do     0    ][yo]   [fo]585:              [ dft / du dft / dv
>  0    dft / dt ][yt]   [ft]586:              by simple
> back-substitution587:            */
>
>  I realized u and v are independent variables, but even so, the first two
> rows should be both containing dfu/dv and dfv/du terms just like the 3rd
> and 4th rows, do I miss some points?

Look at the equations defining the residual (e.g., line 337).  Those
terms are zero.
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