// identity.H
// created by ADP 12/23/03

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#ifndef __RVL_FUNCTION_SETTOCOLUMNOFIDENTITY_
#define __RVL_FUNCTION_SETTOCOLUMNOFIDENTITY_

#include "data.hh"

namespace RVL {

  /** A function object used in the CompassSearch class of gps.H. 
      It sets the ith element to 1, and all the rest to zero.  

      6/17/04 Modified to work correctly when called multiple times.
              Will set the ith element seen to 1, and all others to zero.
	      Thus, still valid when i > n.
*/
template<class Scalar>
class SetToColumnOfIdentity : public UnaryFunctionObject<Scalar> {
private:
  long i;
  long seensofar;
public:
  /** the integer indicates the column of identity to which we set vectors
   */
  SetToColumnOfIdentity(long _i): i(_i), seensofar(0) {}

  /** never reads data
  */
   virtual bool readsData(int i=0) { return false; }

  /** always writes data      
  */
  virtual bool writesData(int i=0) { return true; }

  /** Name method */
  virtual string name() { return "SetToColumnOfIdentity";}

  /** report to exception */
  virtual void write(RVLException & e) {
    e << "SetToColumnOfIdentity with column = " << i << '\n';
  }

  /** report to ostream */
  virtual ostream & write(ostream & str) {
    str << "SetToColumnOfIdentity with column = " << i << '\n';
    return str;
  }

  /** Evaluation method */
  virtual void operator () (LocalDataContainer<Scalar> & A) {
    int n = A.getSize();
    Scalar * d = A.getData();
    for(int j = 0; j < n; j++ )
      d[j] = 0;

    if((i > seensofar)&&(i < n+seensofar ))
      d[i-seensofar] = 1;
  }
};

}
#endif