Line data    Source code

       1             : //# SimACoh.cc: Simulated additive errors
       2             : //# Copyright (C) 1996,1997,1999,2000
       3             : //# Associated Universities, Inc. Washington DC, USA.
       4             : //#
       5             : //# This library is free software; you can redistribute it and/or modify it
       6             : //# under the terms of the GNU Library General Public License as published by
       7             : //# the Free Software Foundation; either version 2 of the License, or (at your
       8             : //# option) any later version.
       9             : //#
      10             : //# This library is distributed in the hope that it will be useful, but WITHOUT
      11             : //# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
      12             : //# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
      13             : //# License for more details.
      14             : //#
      15             : //# You should have received a copy of the GNU Library General Public License
      16             : //# along with this library; if not, write to the Free Software Foundation,
      17             : //# Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
      18             : //#
      19             : //# Correspondence concerning AIPS++ should be adressed as follows:
      20             : //#        Internet email: aips2-request@nrao.edu.
      21             : //#        Postal address: AIPS++ Project Office
      22             : //#                        National Radio Astronomy Observatory
      23             : //#                        520 Edgemont Road
      24             : //#                        Charlottesville, VA 22903-2475 USA
      25             : //#
      26             : //#
      27             : //# $Id$
      28             : 
      29             : #include <casacore/casa/BasicMath/Math.h>
      30             : #include <synthesis/MeasurementComponents/SimACoh.h>
      31             : #include <msvis/MSVis/VisBuffer.h>
      32             : 
      33             : using namespace casacore;
      34             : namespace casa { //# NAMESPACE CASA - BEGIN
      35             : 
      36             : // Note: this simplistic implementation just generates a new random
      37             : // noise value for every call of apply, it doesn't keep track of
      38             : // time and antenna to return the same value if called with the same
      39             : // coordinates. Thus applyInv will only work correctly if
      40             : // called from a separate object in the exact same sequence as apply.
      41             : 
      42           0 : SimACoh::SimACoh(Int seed, Double rms):rndGen_p(seed),
      43             :                                        //noiseDist_p(&rndGen_p, 0.0, square(rms/2.0))
      44           0 : noiseDist_p(&rndGen_p, 0.0, square(rms))
      45             : {
      46           0 : }
      47           0 : VisBuffer& SimACoh::apply(VisBuffer& vb)
      48             : {
      49           0 :   Bool zeroSpacing = false;
      50           0 :   Complex c[4];
      51           0 :   for (Int row=0; row<vb.nRow(); row++) {
      52           0 :     zeroSpacing = false;
      53           0 :     if (vb.uvw()(row)(0) == 0.0 && vb.uvw()(row)(1) == 0.0) {
      54           0 :       zeroSpacing = true;
      55             :     }
      56           0 :     for (Int chn=0; chn<vb.nChannel(); chn++) {
      57           0 :       if (zeroSpacing) {
      58           0 :         for (Int i=0; i<4; i++) c[i]=Complex(1.41421356*noiseDist_p(), 0.0);
      59             :       } else {
      60           0 :         for (Int i=0; i<4; i++) c[i]=Complex(noiseDist_p(),noiseDist_p());
      61             :       }
      62           0 :       CStokesVector noiseCoh(c);
      63             :       
      64           0 :       vb.visibility()(chn,row)+=noiseCoh;
      65             :       
      66             :     }
      67             :   }
      68           0 :   return vb;
      69             : }
      70             : 
      71           0 : VisBuffer& SimACoh::applyInv(VisBuffer& vb)
      72             : {
      73           0 :     Complex c[4];
      74           0 :     for (Int row=0; row<vb.nRow(); row++) {
      75           0 :       for (Int chn=0; chn<vb.nChannel(); chn++) {
      76           0 :         for (Int i=0; i<4; i++) c[i]=Complex(noiseDist_p(),noiseDist_p());
      77           0 :         CStokesVector noiseCoh(c);
      78           0 :         vb.visibility()(chn,row)-=noiseCoh;
      79             :       }
      80             :     }
      81           0 :     return vb;
      82             : }
      83             : 
      84             : } //# NAMESPACE CASA - END
      85             :