Hi.
From your attached files it looks like you have saved the matrix and rhs with
quite few digits. Do you get the same result if you increase the number of
digits you write to your std::ofstream object?
Compare:
https://en.cppreference.com/w/cpp/io/manip/setprecision
Best,
Simon
On 29/07/2023 16:36, Krish wrote:
Hello,
I am solving a problem that has 30 degrees of freedom. The newton update
solution obtained from deal.ii (using both Direct and CG solver) seems to be
less accurate (differs after 4 significant digits) from the newton update
solution obtained from Matlab using the same tangent_matrix and system_rhs. I
am getting the two following solutions from the same tangent_matrix and
system_rhs (data files containing the tangent_matrix and system_rhs attached).
Matlab solution deal.ii solution
0 0
-0.003033422503555 -0.003033560000000
0 0
-0.002439900952733 -0.002439990000000
0 0
-0.002737307578376 -0.002737430000000
0.001007226333711 0.001007240000000
-0.001069740617723 -0.001069780000000
0.001663965890031 0.001663970000000
-0.002605547185476 -0.002605610000000
0.001113032138953 0.001113040000000
-0.001469379092482 -0.001469430000000
0.000916401048149 0.000916380000000
0 0
0.001674445763014 0.001674440000000
0 0
0.001041269520982 0.001041260000000
-0.000000000000000 -0.000000000000000
0 0
0.003033422503555 0.003033560000000
0 0
0.002439900952733 0.002439990000000
0 0
0.002737307578376 0.002737430000000
0.001007226333711 0.001007240000000
0.001069740617723 0.001069780000000
0.001663965890031 0.001663970000000
0.002605547185476 0.002605610000000
0.001113032138953 0.001113040000000
0.001469379092482 0.001469430000000
I am trying to figure out what could be the reason behind it and how to get a
more accurate solution.
Thank you in advance.
Krish
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