[petsc-users] Question on local vec to global vec for dof > 1

[Danyang Su]

On 22/05/2014 12:01 PM, Matthew Knepley wrote:
> On Thu, May 22, 2014 at 1:58 PM, Danyang Su <danyang.su at gmail.com 
> <mailto:danyang.su at gmail.com>> wrote:
>
>     Hi All,
>
>     I have a 1D transient flow problem (1 dof) coupled with energy
>     balance (1 dof), so the total dof per node is 2.
>
>     The whole domain has 10 nodes in z direction.
>
>     The program runs well with 1 processor but failed in 2 processors.
>     The matrix is the same for 1 processor and 2 processor but the rhs
>     are different.
>
>     The following is used to set the rhs value.
>
>     call VecGetArrayF90(x_vec_loc, vecpointer, ierr)
>     vecpointer = (calculate the rhs value here)
>     call VecRestoreArrayF90(x_vec_loc,vecpointer,ierr)
>     call DMLocalToGlobalBegin(da,x_vec_loc,INSERT_VALUES, x_vec_gbl,ierr)
>     call DMLocalToGlobalEnd(da,x_vec_loc,INSERT_VALUES, x_vec_gbl,ierr)
>
>     *Vecview  Correct * *Vecview  Wrong*
>     dof     local node           Process [0] _Process [0] _ /_Process
>     [0] _/
>     1            1 1.395982780116148E-021 1.39598e-021                
>     1.39598e-021
>     1            2 0.000000000000000E+000
>     0                                       0
>     1            3 0.000000000000000E+000 0                           
>                0
>     1            4 5.642372883946980E-037 5.64237e-037                
>     5.64237e-037
>     1            5 0.000000000000000E+000
>     0                                       0
>     1            6 -1.395982780116148E-021 -7.52316e-037
>     -1.39598e-021                       Line A
>     2            1 0.000000000000000E+000 7.52316e-037 0
>     2            2 0.000000000000000E+000 0 0
>     2            3 0.000000000000000E+000 1.68459e-016                  0
>     2            4 4.814824860968090E-035 0.1296 4.81482e-035
>     2            5 0.000000000000000E+000 _/Process [1]/_ Line B
>     2            6 -1.371273884908092E-019 0
>     7.52316e-037                       Line C
>     0           0
>                                            Process [1] 0 1.68459e-016
>     1            1 1.395982780116148E-021 4.81482e-035
>     0.1296                                     Line D
>     1            2 -7.523163845262640E-037 0            
>     1.37127e-019                         Line E
>     1            3 7.523163845262640E-037 -7.22224e-035               
>     -7.22224e-035
>     1            4 0.000000000000000E+000 7.22224e-035                
>     7.22224e-035
>     1            5 1.684590875336239E-016
>     0                                       0
>     1            6 0.129600000000000         
>     128623                            128623
>     2            1 1.371273884908092E-019 0
>     0                                                Line F
>     2            2 -7.222237291452134E-035
>     2            3 7.222237291452134E-035
>     2            4 0.000000000000000E+000
>     2            5 128623.169844761
>     2            6              0.000000000000000E+000
>
>     The red line (Line A, C, D and F) is the ghost values for 2
>     subdomains, but when run with 2 processor, the program treates
>     Line B, C, D, and E as ghost values.
>     *How can I handle this kind of local vector to global vector
>     assembly?*
>
>
> Why are you not using DMDAVecGetArrayF90()? This is exactly what it is 
> for.
Thanks, Matthew.

I tried the following codes but still cannot get the correct global rhs 
vector

call DMDAVecGetArrayF90(da,x_vec_loc,vecpointer1d,ierr)
do i = 1,nvz !nvz is local node amount, here is 6
   vecpointer1d(0,i-1) = x_array_loc(i) !assume x_array_loc is the local 
rhs (the third column in the above mentioned data)
   vecpointer1d(1,i-1) = x_array_loc(i+nvz)
end do
call DMDAVecRestoreArrayF90(da,x_vec_loc,vecpointer1d,ierr)
call DMLocalToGlobalBegin(da,x_vec_loc,INSERT_VALUES, x_vec_gbl,ierr)
call DMLocalToGlobalEnd(da,x_vec_loc,INSERT_VALUES, x_vec_gbl,ierr)


Now the rhs for 1 processor is as follows. It is not what I want.

1.39598e-021
0
-0
-0
-0
-0
5.64237e-037
4.81482e-035
-0
-0
-7.52316e-037
-7.22224e-035
7.52316e-037
7.22224e-035
-0
-0
1.68459e-016
128623
0.1296
0
>
>    Matt
>
>
>     *In fact, the codes can work if the dof and local node is as follows.*
>     dof     local node
>     1            1
>     2            1
>     1            2
>     2            2
>     1            3
>     2            3
>
>     Thanks and regards,
>
>     Danyang
>
>
>
>
> -- 
> What most experimenters take for granted before they begin their 
> experiments is infinitely more interesting than any results to which 
> their experiments lead.
> -- Norbert Wiener

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