TSmallWignerd.cxx

// Author: Marcelo Zimbres Silva <mailto:mzimbres@gmail.com>

/* Copyright (C) 2010, 2011, 2012 Marcelo Zimbres Silva
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or (at
 * your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

// ROOT
#include "TMath.h"
#include "TVirtualFFT.h"

// SWAT

#include "TSmallWignerd.h"
#include "TWignerd.h"

using namespace TMath;

  //////////////////////////////////////////////////////////////////////////
  //                                                                   
  // Calculate small Wigner-d functions using sine and cosine transforms(see
  // TVirtualFFT::SineCosine() for details).  The d`s are sample on the grid
  // beta_k = pi(2k+1)/4B, where B is the band limit. It uses the transform
  // type 1 and 5 for cosine and sine transforms respectively. See tutorials
  // form details on how to use this class.
  //                                                                   
  //////////////////////////////////////////////////////////////////////////

//_____________________________________________________________________
Double_t* TSmallWignerd::Get(const TWignerd& wig,Int_t m,Int_t n,Int_t& nDimRet) const
{
   // Return array with Wigner-d functions. The value l will be taken from wig
   // using TWignerd::GetL(). It must be smaller than L, provided in the
   // constructor. Pointer to array returned is owned by the object and shall
   // not be deleted.

   Int_t l = wig.GetL();

   if (Even(m - n)){

      if ((Abs(n - m) & 3))
         for (Int_t u = 0; u <= l; ++u)
	    fEven->SetPoint(u,-wig.Delta(u,m)*wig.Delta(u,n),0);
      else
	 for (Int_t u = 0; u <= l; ++u)
	    fEven->SetPoint(u,wig.Delta(u,m)*wig.Delta(u,n),0);

      for (Int_t u = l + 1; u < fSize; ++u)
	 fEven->SetPoint(u,0,0);

      fEven->Transform();
       nDimRet=(fEven->GetNdim());
      return fEven->GetPointsReal();
   } else {

      if ((Abs(n - m + 1) & 3))
         for (Int_t u = 0; u < l; ++u)
	    fOdd->SetPoint(u,wig.Delta(u + 1,m)*wig.Delta(u + 1,n),0);
      else
	 for (Int_t u = 0; u < l; ++u)
	    fOdd->SetPoint(u,-wig.Delta(u + 1,m)*wig.Delta(u + 1,n),0);

      for (Int_t u = l; u < fSize; ++u)
	 fOdd->SetPoint(u,0,0);

      fOdd->Transform();
      return fOdd->GetPointsReal();
   } 
}