- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content

i am using PARDISO to solve Ax=b type unsymmetric real sparse matrix. For the give problem if i set boundary conditions as pressure gradient = 0 then PARDISO gives result same as other solvers, but if i set BC's as p=0 then PARDISO gives different(wrong) result as compared to other solvers.

Link Copied

5 Replies

- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content

What differential equation you are solve? Is "p = 0" Dirichle or Neumann boundary condition?

With best regards,

Alexander Kalinkin

- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content

hi,

it is Dirichlet

- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content

What about equation? Could determinant ofresult stiffness matrix is equal zero? If not, could you please attach testcase here?

With best regards,

Alexander Kalinkin

- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content

no the determinant is not zero. The problem looks like (actual problem is large this is an example)

AP11 |
AE11 |
0 |
0 |
AN11 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
X1 |
B1 |
||

AW21 |
AP21 |
AE21 |
0 |
0 |
AN21 |
0 |
0 |
0 |
0 |
0 |
0 |
X2 |
B2 |
||

0 |
AW31 |
AP31 |
AE31 |
0 |
0 |
AN31 |
0 |
0 |
0 |
0 |
0 |
X3 |
B3 |
||

0 |
0 |
AW41 |
AP41 |
0 |
0 |
0 |
AN41 |
0 |
0 |
0 |
0 |
X4 |
B4 |
||

AS12 |
0 |
0 |
0 |
AP12 |
AE12 |
0 |
0 |
AN12 |
0 |
0 |
0 |
X5 |
B5 |
||

0 |
AS22 |
0 |
0 |
AW22 |
AP22 |
AE22 |
0 |
0 |
AN22 |
0 |
0 |
X | X6 |
= | B6 |

0 |
0 |
AS32 |
0 |
0 |
AW32 |
AP32 |
AE32 |
0 |
0 |
AN32 |
0 |
X7 |
B7 |
||

0 |
0 |
0 |
AS42 |
0 |
0 |
AW42 |
AP42 |
0 |
0 |
0 |
AN42 |
X8 |
B8 |
||

0 |
0 |
0 |
0 |
AS13 |
0 |
0 |
0 |
AP13 |
AE13 |
0 |
0 |
X9 |
B9 |
||

0 |
0 |
0 |
0 |
0 |
AS23 |
0 |
0 |
AW23 |
AP23 |
AE23 |
0 |
X10 |
B10 |
||

0 |
0 |
0 |
0 |
0 |
0 |
AS33 |
0 |
0 |
AW33 |
AP33 |
AE33 |
X11 |
B11 |
||

0 |
0 |
0 |
0 |
0 |
0 |
0 |
AS42 |
0 |
0 |
AW43 |
AP43 |
X12 |
B12 |

THIS IS COEFFICIENT MATRIX OF A 4x3 MATRIX.

in order to set right boundary as x=0 (Dirichlet) what i need to do is to set AE41,AE42,AE43 as zero. But when i do this and run PARDISO it gives wrong results (I solved it with gauss siedel and it gives correct result).

Matrix looks like

11 |
21 |
31 |
41 |

12 |
22 |
32 |
42 |

13 |
23 |
33 |
43 |

- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content

Unfortunately, I couldn't find AE41, AE42 and AE43 in table of symbols you wrote. But in my opinion if one want to set Dirichlet boundary condition in some point he need to set zero in correspondent column/string of matrix and change correspondent diagonal element. Nevertheless, could you provide testcase that I could compile and execute for deeper investigation of problem?

With best regards,

Alexander Kalinkin

Topic Options

- Subscribe to RSS Feed
- Mark Topic as New
- Mark Topic as Read
- Float this Topic for Current User
- Bookmark
- Subscribe
- Printer Friendly Page