[sharonyue]

Hi,

In OpenFOAM's test---simpleMatrix.I have this code:

int main(int argc, char *argv[])
{
    simpleMatrix<vector> hmm(3);

    hmm[0][0] = -3.0;
    hmm[0][1] = 10.0;
    hmm[0][2] = -4.0;
    hmm[1][0] = 2.0;
    hmm[1][1] = 3.0;
    hmm[1][2] = 10.0;
    hmm[2][0] = 2.0;
    hmm[2][1] = 6.0;
    hmm[2][2] = 1.0;

    hmm.source()[0] = vector(2.0, 1.0, 3.0);
    hmm.source()[1] = vector(1.0, 4.0, 3.0);
    hmm.source()[2] = vector(0.0, 5.0, 2.0);

    Info<< hmm << endl;
    //Info<< hmm.solve() << endl;
    //Info<< hmm << endl;
    //Info<< hmm.LUsolve() << endl;
    //Info<< hmm << endl;

    //Info<< "End\n" << endl;

    return 0;
}

What does the codes in red mean?Thanks in advance.

This is the result in terminal:

3 3((-3 10 -4)(2 3 10)(2 6 1))
3((2 1 3) (1 4 3) (0 5 2))

[Pedro24]

Your system "hmm" is a linear system of vectors

So you have A x = b

with :
- A the matrix
- "x" the solution and "b" the source term (both are vector of vectors).

The code in red fill the source vector "b" (composed by vector because your system is a simpleMatrix of vectors)

    hmm.source()[0] = vector(2.0, 1.0, 3.0);
    hmm.source()[1] = vector(1.0, 4.0, 3.0);
    hmm.source()[2] = vector(0.0, 5.0, 2.0);

Pierre

[wenxu]

Originally Posted by Pedro24

Your system "hmm" is a linear system of vectors

So you have A x = b

with :
- A the matrix
- "x" the solution and "b" the source term (both are vector of vectors).

The code in red fill the source vector "b" (composed by vector because your system is a simpleMatrix of vectors)

    hmm.source()[0] = vector(2.0, 1.0, 3.0);
    hmm.source()[1] = vector(1.0, 4.0, 3.0);
    hmm.source()[2] = vector(0.0, 5.0, 2.0);

Pierre

hi，Pedro24。but A=3 3((-3 10 -4)(2 3 10)(2 6 1)) multiply with x1=(-0.452599 1.12232 -0.149847) (the result got by the test code) do not equal to b1=(2 1 3). why? i have misunderstand this? please help me. Thank you!!!

[bigorange]

Originally Posted by wenxu

hi，Pedro24。but A=3 3((-3 10 -4)(2 3 10)(2 6 1)) multiply with x1=(-0.452599 1.12232 -0.149847) (the result got by the test code) do not equal to b1=(2 1 3). why? i have misunderstand this? please help me. Thank you!!!

Hi wenxu, have you gotten the answer for this problem?

[Pedro24]

Originally Posted by bigorange

Hi wenxu, have you gotten the answer for this problem?

Hi all,

I didn't see this message few years ago but you cannot separate one solution vector from the others (the system has 9 dependent unknowns, and not 3 x 3 unknwowns). When you run the code, you get :

3((-0.452599 1.12232 -0.149847) (0.125382 0.452599 0.345566) (0.152905 0.0397554 0.2263))

as solution. I you multiply :

A =

   -3   10   -4
    2    3   10
    2    6    1

with the given solution :

x =

  -0.452599   1.122320  -0.149847
   0.125382   0.452599   0.345566
   0.152905   0.039755   0.226300

you will get the source term (which is also a matrix, i.e. a vector of vectors) :

A * x =

   2.0000e+00   1.0000e+00   3.0000e+00
   1.0000e+00   4.0000e+00   3.0000e+00
  -1.0000e-06   5.0000e+00   2.0000e+00

Sincerely,

Pierre