Re: [deal.II] Question about complex value finite element

2020-08-16 Thread yuesu jin
Sure, I will add my progress following this email.
Best regards,

On Sun, Aug 16, 2020 at 7:47 PM Wolfgang Bangerth 
wrote:

> On 8/16/20 6:38 PM, yuesu jin wrote:
> > Thank you very much! I found step-62 yesterday and I have
> compared the
> > difference between them.  I want to write two versions and compare their
> CPU
> > time to get an exact result.
>
> That would be interesting to hear about -- please let us know what you
> find!
> Best
>   W.
>
> --
> 
> Wolfgang Bangerth  email: bange...@colostate.edu
> www: http://www.math.colostate.edu/~bangerth/
>
> --
> The deal.II project is located at http://www.dealii.org/
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> .
>


-- 
Yuesu Jin,
Ph.D student,
University of Houston,
College of Natural Sciences and Mathematics,
Department of Earth and Atmospheric Sciences,
Houston, Texas 77204-5008
346-404-2062

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Re: [deal.II] Question about complex value finite element

2020-08-16 Thread Wolfgang Bangerth

On 8/16/20 6:38 PM, yuesu jin wrote:
    Thank you very much! I found step-62 yesterday and I have compared the 
difference between them.  I want to write two versions and compare their CPU 
time to get an exact result.


That would be interesting to hear about -- please let us know what you find!
Best
 W.

--

Wolfgang Bangerth  email: bange...@colostate.edu
   www: http://www.math.colostate.edu/~bangerth/

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Re: [deal.II] Question about complex value finite element

2020-08-16 Thread yuesu jin
Dear Dr. Bangerth,
   Thank you very much! I found step-62 yesterday and I have compared the
difference between them.  I want to write two versions and compare their
CPU time to get an exact result.
Best regards,
Yuesu

On Sun, Aug 16, 2020 at 7:19 PM Wolfgang Bangerth 
wrote:

> Yuesu,
>
> >I am adding an absorbing boundary condition like step-24 did in the
> > frequency domain, in which the time derivative gives a complex term.  I
> also
> > found the complex acoustic wave problem step-29 which splits the complex
> wave
> > function into two real parts.
> >What I want to know is what if I directly set up the matrix and rhs
> vector
> > as complex ? Why does step-29 says "/it is often more convenient
> to
> > split complex valued functions into their real and imaginary parts and
> use
> > separate scalar finite element fields for discretizing each one of
> them/" ?
>
> The problem is that we don't have iterative solvers for problems in which
> the
> matrix and vectors store complex values. We can, however, use PETSc's
> complex-valued solvers as well as the SparseDirectUMFPACK solver. I think
> you
> probably want to look at step-62 and step-58 for other options.
>
> Best
>   W.
>
>
> --
> 
> Wolfgang Bangerth  email: bange...@colostate.edu
> www: http://www.math.colostate.edu/~bangerth/
>
> --
> The deal.II project is located at http://www.dealii.org/
> For mailing list/forum options, see
> https://groups.google.com/d/forum/dealii?hl=en
> ---
> You received this message because you are subscribed to the Google Groups
> "deal.II User Group" group.
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> To view this discussion on the web visit
> https://groups.google.com/d/msgid/dealii/168267e0-9fbd-fc96-e780-f697856b5572%40colostate.edu
> .
>


-- 
Yuesu Jin,
Ph.D student,
University of Houston,
College of Natural Sciences and Mathematics,
Department of Earth and Atmospheric Sciences,
Houston, Texas 77204-5008
346-404-2062

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Re: [deal.II] Question about complex value finite element

2020-08-16 Thread Wolfgang Bangerth

Yuesu,

   I am adding an absorbing boundary condition like step-24 did in the 
frequency domain, in which the time derivative gives a complex term.  I also 
found the complex acoustic wave problem step-29 which splits the complex wave 
function into two real parts.
   What I want to know is what if I directly set up the matrix and rhs vector 
as complex ? Why does step-29 says "/it is often more convenient to 
split complex valued functions into their real and imaginary parts and use 
separate scalar finite element fields for discretizing each one of them/" ?


The problem is that we don't have iterative solvers for problems in which the 
matrix and vectors store complex values. We can, however, use PETSc's 
complex-valued solvers as well as the SparseDirectUMFPACK solver. I think you 
probably want to look at step-62 and step-58 for other options.


Best
 W.


--

Wolfgang Bangerth  email: bange...@colostate.edu
   www: http://www.math.colostate.edu/~bangerth/

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[deal.II] Question about complex value finite element

2020-08-14 Thread yuesu jin
Dear all,
  I am adding an absorbing boundary condition like step-24 did in the
frequency domain, in which the time derivative gives a complex term.  I
also found the complex acoustic wave problem step-29 which splits the
complex wave function into two real parts.
  What I want to know is what if I directly set up the matrix and rhs
vector as complex ? Why does step-29 says "*it is often more
convenient to split complex valued functions into their real and imaginary
parts and use separate scalar finite element fields for discretizing each
one of them*" ?
Best wishes,

-- 
Yuesu Jin,
Ph.D student,
University of Houston,
College of Natural Sciences and Mathematics,
Department of Earth and Atmospheric Sciences,
Houston, Texas 77204-5008
346-404-2062

-- 
The deal.II project is located at http://www.dealii.org/
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