<font class="Apple-style-span" size="2" face="arial, helvetica, sans-serif">Hello!</font><div><font class="Apple-style-span" size="2" face="arial, helvetica, sans-serif">Help me please to solve my tiny problem with dmmg.</font></div>
<div><font class="Apple-style-span" size="2" face="arial, helvetica, sans-serif"><br></font></div><div><font class="Apple-style-span" size="2" face="arial, helvetica, sans-serif">In the example src/ksp/ksp/examples/tutorials/ex22.c, which is discussed on the 111th page of users manual, we use function </font></div>
<div><font class="Apple-style-span" size="2" face="'courier new', monospace">(line 36): DACreate3d(PETSC_COMM_WORLD,DA_NONPERIODIC,DA_STENCIL_STAR,-3,-3,-3,PETSC_DECIDE,PETSC_DECIDE,PETSC_DECIDE,1,1,0,0,0,&da);</font></div>
<div><font class="Apple-style-span" size="2" face="arial, helvetica, sans-serif">to "<i>create the DA that stores information about the coarsest grid you wish to use</i>".</font></div><div><font class="Apple-style-span" size="2" face="arial, helvetica, sans-serif">We can see that negative dimension values (<span class="Apple-style-span" style="background-color: rgb(255, 255, 255); ">-M, -N, -P) </span>are used <span class="Apple-style-span" style="background-color: rgb(255, 255, 255); "> "<i>to indicate that it may be set to a different value from the command line with -da_grid_x <M> -da_grid_y <N> -da_grid_z <P>". </i></span></font></div>
<div><font class="Apple-style-span" size="2" face="arial, helvetica, sans-serif">The question is: when I use -da_grid_ M,N,P options as the size of the coarsest matrix, what's the size of the finest (most accurate, original problem) matrix?</font></div>
<div><font class="Apple-style-span" size="2" face="arial, helvetica, sans-serif"><br></font></div><div><font class="Apple-style-span" size="2" face="arial, helvetica, sans-serif">I've tried to clear this up, using VecVew on the residual vector and figured out, that when i'm using M,N,P as input parameters (so define the coarsest grid as field of M*N*P dots), I get the residual vector of si<font class="Apple-style-span" style="line-height: 23px;">ze (4*M-3)*(4*N-3)*(4*P-3).</font></font></div>
<div><font class="Apple-style-span" style="line-height: 23px;" size="2" face="arial, helvetica, sans-serif">Is my result correct? If yes, could you please explain why it happens in this way.</font></div><div><font class="Apple-style-span" style="line-height: 23px;" size="2" face="arial, helvetica, sans-serif"><br>
</font></div><div><font class="Apple-style-span" style="line-height: 23px;" size="2" face="arial, helvetica, sans-serif">Sorry if my question is incorrect. I could mix up everything at all.</font></div><div><font class="Apple-style-span" style="line-height: 23px;" size="2" face="arial, helvetica, sans-serif">Thanks in advance!</font></div>
<div><font class="Apple-style-span" face="'Times New Roman'" size="4" style="line-height: 23px;"><br></font></div><div>-- <br><span style="border-collapse:collapse;font-family:arial, sans-serif;font-size:13px"><div>
<span style="border-collapse:collapse;font-family:arial, sans-serif;font-size:13px"><div>Best regards,</div><div>Alexey Ryazanov</div><div>______________________________________</div><div><span style="color:rgb(51, 51, 51);font-family:Arial, Helvetica, sans-serif"><font size="1">Nuclear Safety Institute of Russian Academy of Sciences </font></span></div>
</span></div><div><br></div></span><br>
</div>