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Thanks.

1 Solution

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d_Helmholtz_3D is the direct solver of matrix correspond of 7-point grid Helmholtz equation. So its provide accuracy based on floating operations.

With best regards,

Alexander Kalinkin

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d_Helmholtz_3D is the direct solver of matrix correspond of 7-point grid Helmholtz equation. So its provide accuracy based on floating operations.

With best regards,

Alexander Kalinkin

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since it is double precision, does it mean the accuracy is 1E-16?

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Not equal but about it.

With best regards,

Alexander Kalinkin

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I checked the accuracy of d_Helmholtz_3D and it was much much larger than 1E-16. Since the solver uses a standard seven-point discretization, I verified the accuracy by the following code. (I have a uniform mesh for my problem.)

[cpp]for ( k=1; k

When I print res, the residual is about 1E-1. Is there something that I have to be careful when using the function? I need to have an accuracy about 1E-16. Please advise.

Thanks,

Ahmad

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To verify it I need to have full example with rhs and boundary condition. Could you provide this example to me by e'mail or by private answer?

With best regards,

Alexander Kalinkin

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I found a bug in my code which misled me to the see large residuals. I fixed it and the error now is about 1E-15.

Thanks,

Ahmad

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Nice to hear it, feel free to ask any question about PL in particular and MKL in general.

With best regards,

Alexander Kalinkin

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I have another question. The solver is for uniform mesh. Does this mean that it has to have dx=dy=dz? Or we can have dx!=dy!=dz (constant dx, dy, dz everywhere in the domain)?

Thanks,

Ahmad

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The uniform mesh mean that all mesh steps are equals in one direction, but mesh sizes for different dimension could be differ. For example hx=0.2, hy=0.5, hz=0.1.

With best regards,

Alexander Kalinkin

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Thanks,

Ahmad

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The main information could be in paper prepared by us a several years ago so feel free to use it.

With best regards,

Alexander Kalinkin

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Thanks. You helped me a lot.

Best,

Ahmad

Best,

Ahmad

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I didn't find the method by which the library solves the system. Is it gradient bi-conjugate, multigrid, overrelaxation, or Fourier? I would appreciate it.

Thanks,

Ahmad

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Poisson library based on Fourier decomposition for elliptic problems with separable variables.

With best regards,

Alexander Kalinkin

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