mc_interp.cc

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/* Copyright (C) 2005-2012 Cory Davis <cory@met.ed.ac.uk>
                            
   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 2, 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
   USA. */



/*===========================================================================
  === File description 
  ===========================================================================*/

/*===========================================================================
  === External declarations
  ===========================================================================*/
#include "mc_interp.h"
#include "logic.h"
#include "montecarlo.h"



Numeric SLIData2::interpolate(Numeric x1, Numeric x2) const
{
  GridPos gp1,gpl,gpr;
  Vector itw1(2),itwl(2),itwr(2);
  Numeric yl,yr;
  //Get interpolation weights for x1 interpolation
  gridpos(gp1,this->x1a,x1);
  interpweights(itw1,gp1);
  //Get y values on bounding x1 grid points for desired x2
  gridpos(gpl,this->x2a[gp1.idx],x2);
  interpweights(itwl,gpl);
  gridpos(gpr,this->x2a[gp1.idx+1],x2);
  interpweights(itwr,gpr);
  yl=interp(itwl,this->ya[gp1.idx],gpl);
  yr=interp(itwr,this->ya[gp1.idx+1],gpr);
  //interpolate these two y values useing x1 interpolation weights
  return itw1[0]*yl+itw1[1]*yr;
}

//void SLIData2::check() const
//{
//  Index nx1=this->x1a.nelem();
//  assert(nx1>0);  
//}


ostream& operator<< (ostream& os, const SLIData2& /* sli */)
{
  os << "SLIData2    : Output operator not implemented";
  return os;
}









                

void interp(MatrixView tia,
            ConstVectorView itw,
            const ArrayOfMatrix& a,    
            const GridPos&  tc )
{
  DEBUG_ONLY (const Numeric sum_check_epsilon = 1e-6);

  assert(is_size(itw,2));       // We need 2 interpolation
                                // weights.

  // Check that interpolation weights are valid. The sum of all
  // weights (last dimension) must always be approximately one.
  assert( is_same_within_epsilon( itw.sum(),
                                  1,
                                  sum_check_epsilon ) );
  
  Index anr = a[0].nrows();
  Index anc = a[0].ncols();
  
  assert(tia.nrows() == anr);
  assert(tia.ncols() == anc);
  
  for (Index inr = 0; inr < anr; inr++)
    for (Index inc = 0; inc < anc; inc++)
    {
      tia(inr,inc) = a[tc.idx](inr,inc)*itw[0] + a[tc.idx+1](inr,inc)*itw[1];
    }
}               



void interp(VectorView tia,
            ConstVectorView itw,
            const ArrayOfVector& a,    
            const GridPos&  tc )
{
  DEBUG_ONLY (const Numeric sum_check_epsilon = 1e-6);
  assert(is_size(itw,2));       // We need 2 interpolation
                                // weights.

  // Check that interpolation weights are valid. The sum of all
  // weights (last dimension) must always be approximately one.
  assert( is_same_within_epsilon( itw.sum(),
                                  1,
                                  sum_check_epsilon ) );
  
  Index an = a[0].nelem();
  
  assert(tia.nelem() == an);

  for ( Index i=0; i<an; ++i )
  {
    tia[i] = a[tc.idx][i]*itw[0] + a[tc.idx+1][i]*itw[1];
  }
}               

void interp_scat_angle_temperature(//Output:
                                   VectorView pha_mat_int,
                                   Numeric& theta_rad,
                                   //Input:
                                   const SingleScatteringData& scat_data,
                                   const Numeric& za_sca,
                                   const Numeric& aa_sca,
                                   const Numeric& za_inc,
                                   const Numeric& aa_inc,
                                   const Numeric& rtp_temperature
                                   )
{
  Numeric ANG_TOL=1e-7;

  //Calculate scattering angle from incident and scattered directions.
  //The two special cases are implemented here to avoid NaNs that can 
  //sometimes occur in in the acos... formula in forward and backscatter
  //cases. CPD 5/10/03.
  
  if(abs(aa_sca-aa_inc)<ANG_TOL)
    {
      theta_rad=DEG2RAD*abs(za_sca-za_inc);
    }
  else if (abs(abs(aa_sca-aa_inc)-180)<ANG_TOL)
    {
      theta_rad=DEG2RAD*(za_sca+za_inc);
      if (theta_rad>PI){theta_rad=2*PI-theta_rad;}
    }
  else
    {
      const Numeric za_sca_rad = za_sca * DEG2RAD;
      const Numeric za_inc_rad = za_inc * DEG2RAD;
      const Numeric aa_sca_rad = aa_sca * DEG2RAD;
      const Numeric aa_inc_rad = aa_inc * DEG2RAD;
      
      // cout << "Interpolation on scattering angle" << endl;
      assert (scat_data.pha_mat_data.ncols() == 6);
      // Calculation of the scattering angle:
      theta_rad = acos(cos(za_sca_rad) * cos(za_inc_rad) + 
                       sin(za_sca_rad) * sin(za_inc_rad) * 
                       cos(aa_sca_rad - aa_inc_rad));
   }
      const Numeric theta = RAD2DEG * theta_rad;
      
  // Interpolation of the data on the scattering angle:
 
  GridPos thet_gp;
  gridpos(thet_gp, scat_data.za_grid, theta);
  GridPos t_gp;
  
  if( scat_data.T_grid.nelem() == 1)
    {
      Vector itw(2);
      interpweights(itw, thet_gp);
      
      for (Index i = 0; i < 6; i++)
      {
        pha_mat_int[i] = interp(itw, scat_data.pha_mat_data(0,0,joker, 0, 0, 0, i),thet_gp);
      }
    }
  else
    {
      gridpos(t_gp, scat_data.T_grid, rtp_temperature);
          
      Vector itw(4);
      interpweights(itw, t_gp,thet_gp);

      for (Index i = 0; i < 6; i++)
        {
          pha_mat_int[i] = interp(itw, scat_data.pha_mat_data(0,joker,joker, 0, 0, 0, i), 
                                  t_gp,thet_gp);
        }
    }
}