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Hi Jed, <br>
<br>
I have attached the output runing under linux. It's only running
with 1 processor. I am using runge kutta 3rd order to solve my
problem, so there's 3 substeps per time step ie I need to solve the
x/y momentum eqns 3 times per time step.<br>
<br>
The error occurs at t=2, substep=2. It stated in the output.<br>
<br>
Btw, I am solving the x and y momentum eqns separately, since they
are independent of one another. How can I solve it together?<br>
<br>
My code is:<br>
<br>
call
MatSetValues(A_semi_x,1,II,1,JJ,semi_mat_x(k,kk),INSERT_VALUES,ierr)
...<br>
<br>
call MatAssemblyBegin(A_semi_x,MAT_FINAL_ASSEMBLY,ierr)<br>
call MatAssemblyEnd(A_semi_x,MAT_FINAL_ASSEMBLY,ierr)<br>
<br>
call KSPGetPC(ksp_semi_x,pc_semi_x,ierr)<br>
ksptype=KSPBCGS<br>
call KSPSetType(ksp_semi_x,ksptype,ierr)<br>
call KSPSetFromOptions(ksp_semi_x,ierr)<br>
<br>
tol=1.e-5<br>
<br>
call
KSPSetTolerances(ksp_semi_x,tol,PETSC_DEFAULT_DOUBLE_PRECISION,PETSC_DEFAULT_DOUBLE_PRECISION,PETSC_DEFAULT_INTEGER,ierr)<br>
<br>
exactly the same for y...<br>
<br>
call VecAssemblyBegin(b_rhs_semi_x,ierr)<br>
call VecAssemblyEnd(b_rhs_semi_x,ierr)<br>
<br>
call VecAssemblyBegin(xx_semi_x,ierr)<br>
call VecAssemblyEnd(xx_semi_x,ierr)<br>
<br>
call
KSPSetOperators(ksp_semi_x,A_semi_x,A_semi_x,SAME_NONZERO_PATTERN,ierr)<br>
call KSPSolve(ksp_semi_x,b_rhs_semi_x,xx_semi_x,ierr)<br>
call KSPGetConvergedReason(ksp_semi_x,reason,ierr)<br>
<br>
exactly the same for y...<br>
<br>
Thanks alot!<br>
<pre class="moz-signature" cols="72">Yours sincerely,
TAY wee-beng</pre>
<br>
On 9/7/2011 12:26 AM, Jed Brown wrote:
<blockquote
cite="mid:CAM9tzSmotqVyg8q3kVBa+rONJQTF2Q_b7KmBibR6ZOfefnjwPA@mail.gmail.com"
type="cite">
<div class="gmail_quote">On Fri, Jul 8, 2011 at 17:17, TAY
wee-beng <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:zonexo@gmail.com">zonexo@gmail.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt
0.8ex; border-left: 1px solid rgb(204, 204, 204);
padding-left: 1ex;">
<div bgcolor="#ffffff" text="#000000"> Hi Jed,<br>
<br>
This is my output when the error happens for gmres:<br>
<br>
2 KSP preconditioned resid norm 1.556688898463e+007 true
resid norm 2.58995443<br>
8801e+003 ||Ae||/||Ax|| 1.232088736212e+003<br>
2 KSP preconditioned resid norm 1.556688898463e+007 true
resid norm 2.58995443<br>
8801e+003 ||Ae||/||Ax|| 1.232088736212e+003<br>
3 KSP preconditioned resid norm 1.207952812560e+003 true
resid norm 9.05939430<br>
1179e+003 ||Ae||/||Ax|| 4.309719703237e+003<br>
3 KSP preconditioned resid norm 1.207952812560e+003 true
resid norm 9.05939430<br>
1179e+003 ||Ae||/||Ax|| 4.309719703237e+003 3 KSP
preconditioned resid norm 1.207952812560e+003 true resid
norm 9.05939430<br>
1179e+003 ||Ae||/||Ax|| 4.309719703237e+003<br>
3 KSP preconditioned resid norm 1.207952812560e+003 true
resid norm 9.05939430<br>
1179e+003 ||Ae||/||Ax|| 4.309719703237e+003<br>
3 KSP preconditioned resid norm 1.207952812560e+003 true
resid norm 9.05939430<br>
1179e+003 ||Ae||/||Ax|| 4.309719703237e+003<br>
4 KSP preconditioned resid norm 3.815055004710e+001 true
resid norm 1.96385966<br>
1729e+002 ||Ae||/||Ax|| 9.342439899591e+001<br>
4 KSP preconditioned resid norm 3.815055004710e+001 true
resid norm 1.96385966<br>
1729e+002 ||Ae||/||Ax|| 9.342439899591e+001<br>
4 KSP preconditioned resid norm 3.815055004710e+001 true
resid norm 1.96385966<br>
1729e+002 ||Ae||/||Ax|| 9.342439899591e+001<br>
4 KSP preconditioned resid norm 3.815055004710e+001 true
resid norm 1.96385966<br>
1729e+002 ||Ae||/||Ax|| 9.342439899591e+001<br>
4 KSP preconditioned resid norm 3.815055004710e+001 true
resid norm 1.96385966<br>
1729e+002 ||Ae||/||Ax|| 9.342439899591e+001<br>
</div>
</blockquote>
<div><br>
</div>
<div>Why is the same line output multiple times? Do you have an
MPI problem?</div>
<div><br>
</div>
<div>This convergence looks funky; I suspect your preconditioner
is singular and/or nonlinear. Please send -ksp_view output as
you are running here and with -pc_type asm -sub_pc_type lu.</div>
<div> </div>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt
0.8ex; border-left: 1px solid rgb(204, 204, 204);
padding-left: 1ex;">
<div bgcolor="#ffffff" text="#000000"> <br>
for fgmres:<br>
<br>
34 KSP preconditioned resid norm 2.428114102327e-005 true
resid norm 3.35941610<br>
6265e-005 ||Ae||/||Ax|| 1.598129588716e-005<br>
34 KSP preconditioned resid norm 2.428114102327e-005 true
resid norm 3.35941610<br>
6265e-005 ||Ae||/||Ax|| 1.598129588716e-005<br>
35 KSP preconditioned resid norm 2.200715659545e-005 true
resid norm 3.88294769<br>
5703e-005 ||Ae||/||Ax|| 1.847182191086e-005<br>
35 KSP preconditioned resid norm 2.200715659545e-005 true
resid norm 3.88294769<br>
5703e-005 ||Ae||/||Ax|| 1.847182191086e-005<br>
35 KSP preconditioned resid norm 2.200715659545e-005 true
resid norm 3.88294769<br>
5703e-005 ||Ae||/||Ax|| 1.847182191086e-005<br>
35 KSP preconditioned resid norm 2.200715659545e-005 true
resid norm 3.88294769<br>
5703e-005 ||Ae||/||Ax|| 1.847182191086e-005<br>
35 KSP preconditioned resid norm 2.200715659545e-005 true
resid norm 3.88294769<br>
5703e-005 ||Ae||/||Ax|| 1.847182191086e-005<br>
36 KSP preconditioned resid norm 2.011575409369e-005 true
resid norm 3.89282805<br>
6204e-005 ||Ae||/||Ax|| 1.851882441357e-005<br>
36 KSP preconditioned resid norm 2.011575409369e-005 true
resid norm 3.89282805<br>
6204e-005 ||Ae||/||Ax|| 1.851882441357e-005<br>
36 KSP preconditioned resid norm 2.011575409369e-005 true
resid norm 3.89282805<br>
6204e-005 ||Ae||/||Ax|| 1.851882441357e-005<br>
36 KSP preconditioned resid norm 2.011575409369e-005 true
resid norm 3.89282805<br>
6204e-005 ||Ae||/||Ax|| 1.851882441357e-005<br>
36 KSP preconditioned resid norm 2.011575409369e-005 true
resid norm 3.89282805<br>
6204e-005 ||Ae||/||Ax|| 1.851882441357e-005<br>
<br>
Btw, I am solving the x and y momentum eqns so there 's 2
eqns to solve.</div>
</blockquote>
<div><br>
</div>
<div>Do you solve them separately or both at once? (We usually
recommend the latter.)</div>
<div> </div>
</div>
</blockquote>
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