[Nek5000-users] How to obtain spectral coefficients and basis

[nek5000-users at lists.mcs.anl.gov]

Andrew,

Thanks for the reply. And can you please confirm that the polynomials 
used are Chebyshev?

On 12/8/2015 11:26 AM, nek5000-users at lists.mcs.anl.gov wrote:
> Hello,
>
> If I've understood you propely, you can see all the collocation points 
> and weights in the file coef.f (subroutine genwz).
>
> Andrew
>
> 2015-12-07 4:23 GMT+01:00 <nek5000-users at lists.mcs.anl.gov 
> <mailto:nek5000-users at lists.mcs.anl.gov>>:
>
>     Hello,
>
>     I'm trying to represent the solution, either velocity or
>     temperature, in terms of spectral basis, i.e.
>
>     $u=\Sigma a_i \phi_i $ with $\phi_i$ as the basis and $a_i$ as the
>     coefficients.
>
>     I have two questions:
>
>     1) (a naive one!) Which basis is being used in Nek5000? I assume
>     it is Chebyshev polynomials. Is that true? If not, what is the basis?
>
>     2) How can I retrieve the coefficients $a_i$? Also, is there a way
>     to access such coefficients during the solution, say by writing
>     them to a file?
>
>     I really appreciate the responses. As a side note, I'd like to use
>     DNS data for model reduction.
>
>     Many thanks,
>     Saleh
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>
>
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