[Nek5000-users] Computing higher order derivatives

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

On Wed, Jan 15, 2014 at 6:24 PM, <nek5000-users at lists.mcs.anl.gov> wrote:

> Hi Praveen,
>
> To compute continuous weak approximations to du/dy (say), you
> would do the following:
>
>       call gradm1(ux,uy,uz,u)
>
>       n = nx1*ny1*nz1*nelv
>       call col2  (uy,bm1,n)
>       call dssum (uy,nx1,ny1,nz1)
>       call col2  (uy,binvm1,n)
>
> assuming all arrays appropriately declared.
>

Thank you. I will try this.

I realized that I am saving the solution in 4 bytes which could lead to
loss of precision. I tried to save the averaged solution in 8 bytes with
following code in usrchk

      param(63) = 8.0

      call avg_all()

      param(63) = 0.0


But the "avg*" files still are not saved in 8 bytes. If I set param(63)=8
in rea file then it works.

Best
praveen
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