[Nek5000-users] Transfer data from an nelx*nely*nelz array of Nth-order to an n*n*n array for FFT analysis

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

Hi neks !

For a given velocity field (vx(1:lx1,1:ly1,1:lz1,1:lelv),vy(1:lx1,1:ly1,1:lz1,1:lelv),vz(1:lx1,1:ly1,1:lz1,1:lelv))
i would like to calculate the energy spectrum, this implies FFT transformation on regular arrays vx(1:n,1:n,1:n),vy(1:n,1:n,1:n),vz(1:n,1:n,1:n) (need deltax=deltay=deltaz=cst).
On the emailing-list it has been said : 

"We do have off-line serial routines
that can transfer data from an nelx x nely x nelz array of Nth-order
elements to an nxnxn array - this allows for analysis by FFTs etc"


Can you please tell me more about this ? What are these routines ??
B.regards
Can