From help-request at octave dot org Thu Apr 13 08:44:05 2006
Subject: Oct Indexing of individual elements in an NDArray
From: John Weatherwax <weatherwax at ll dot mit dot edu>
To: help at octave dot org
Date: Thu, 13 Apr 2006 08:21:40 -0500

Hello,
    I would like to be able to access the individual elements in an 
NDArray (to fill them with another function) but have been unable to 
figure out how to make this work.  I'm sure this is an easy answer but 
could someone point me in the correct direction?

  Effectively I need code like the following

  dim_vector dvp(NPDE,NX,NY); // dimension of each solution page
  // declare the NDArray to be filled (u T(ime) S(tep) solution):
  NDArray uTS( dvp );

    for( int ix=0; ix < NX; ix++ ){
      for( int iy=0; iy < NY; iy++ ){
      // Compute the data used to fill the NDArray ...
      ColumnVector uinit_out = pdetwo_uinit_function( xbkpt(ix), 
ybkpt(iy) );
      // Fill the NDArray:
      for( int ip=0; ip < NPDE; ip++ ){
        uTS(ix,iy,ip) = 
uinit_out(ip);                                                                                             
// <- this line is not correct?  How do?
      }
    }
  }

  BTW, I have tried something like the following:

  // Fill uTS with the initial conditions (for convenience):
  for( int ix=0; ix < NX; ix++ ){
    for( int iy=0; iy < NY; iy++ ){
      ColumnVector uinit_out = pdetwo_uinit_function( xbkpt(ix), 
ybkpt(iy) );
      //octave_stdout << "..." << uinit_out << "\n";
      for( int ip=0; ip < NPDE; ip++ ){
      Array<idx_vector> idx(3);
      idx(0)=idx_vector(ip);
      idx(1)=idx_vector(ix);
      idx(2)=idx_vector(iy);
      uTS.index(idx,2.0);
      }
    }
  }

Sorry for my ignorance and I would be very appreciative of any light 
anyone could shed on this simple problem.

Thanks,

John Weatherwax

-- 

John L. Weatherwax

Lincoln Laboratory, Massachusetts Institute of Technology
244 Wood Street
Lexington, MA 02420-9108 USA

Phone : 781-981-5370
Fax   : 781-981-4739
Email : weatherwax at ll dot mit dot edu

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