[Users] SphericalHarmonicRecon and SphericalHarmonicReconGen

[Yosef Zlochower]

On 07/13/2017 11:25 AM, Frank Loeffler wrote:
> On Thu, Jul 13, 2017 at 11:14:00AM -0400, Yosef Zlochower wrote:
>>  if (minval(abs(zeta - dcmplx(1,1))) < 1.0d-10) then
>>         Tarr = minloc(abs(stereo_q(:,1)-1.))
>>         loc_q = Tarr(1)
>>         Tarr = minloc(abs(stereo_p(1,:)-1.))
>>         loc_p = Tarr(1)
>>         if (abs(zeta(loc_q,loc_p) - dcmplx(1.,1.)) .gt. 1d-10) then
>>            call CCTK_WARN(0, " Error ")
>>         endif
>>
>>      endif
>> or one complex one (zeta). With zeta = q + i * p. The code is checking
>> that if zeta == 1+i anywhere, that it is equal to 1 + i at the point
>> where q=1 and p=1.
> 
> I don't quite understand something about that code. It looks for a 
> location where q is closest to 1, and one where p is closest to i:
> 
>   minloc(abs(stereo_q(:,1)-1.))
>   minloc(abs(stereo_p(1,:)-1.))
> 
> It then assumes the respective 'other' coordinate is the one it should 
> be looking at:
> 
>   zeta(loc_q,loc_p)
> 
> Is this really always the case (could be, if this comes from some kind 
> of known grid setup, but this is not apparent from the code).
> 


I don't understand the test either, but it should be the case that
dble(zeta) = stereo_q
and dimag(zeta) = stereo_p

zeta is initialized as  zeta      = dcmplx(stereo_q,stereo_p)
in pittnullcode/NullGrid/src/NullGrid_InitCoord.F90

> Frank
>