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Difference between GMRES and TDMA

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Old   January 3, 2007, 15:27
Default Difference between GMRES and TDMA
  #1
Mehdi
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Hi,

I am going to change my solver from TDMA to GMRES. Does anyone know which one is faster. I do not want to waiste my time by changing my solver.

Is there any big difference in CPU time if I use GMRES?

Regards,
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Old   January 4, 2007, 11:56
Default Re: Difference between GMRES and TDMA
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raju
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GMRES by itself is very inefficient (as far as my experience goes). It needs a good preconditioner. So you must have some knowledge about preconditioners.

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Old   January 4, 2007, 12:56
Default Re: Difference between GMRES and TDMA
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Praveen. C
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If you are using TMDA, I guess your matrix is triangular. TMDA is the best scheme in this case.
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Old   January 5, 2007, 11:45
Default Re: Difference between GMRES and TDMA
  #4
Luca Cavagna
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Yes I agree with raju and praveen. If you have a tridiagonal matrix keep on using the TDMA which has been specifically developed. As raju said GMRES is not the solution to every problem! You need a good preconditioner to reduce the number of iteration and you may run out of memory is you have many degrees of freedom. Luca
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