EvtValError.hh

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/*******************************************************************************
 * Project: BaBar detector at the SLAC PEP-II B-factory
 * Package: EvtGenBase
 *    File: $Id: EvtValError.hh,v 1.1.1.2 2007/10/26 05:03:14 pingrg Exp $
 *  Author: Alexei Dvoretskii, dvoretsk@slac.stanford.edu, 2001-2002
 *
 * Copyright (C) 2002 Caltech
 *******************************************************************************/
 
// Value and its associated error. E.g. this could be interval size and
// the error associated with numerical integration.
 
#ifndef EVT_VAL_ERROR_HH
#define EVT_VAL_ERROR_HH
 
#include <assert.h>
#include <iostream>
#include <math.h>
 
class EvtValError {
 
public:
  EvtValError();
  EvtValError( double val );
  EvtValError( double val, double err );
  EvtValError( const EvtValError& other );
  ~EvtValError();
 
  inline int    valueKnown() const { return _valKnown; }
  inline double value() const {
    assert( _valKnown );
    return _val;
  }
  inline int    errorKnown() const { return _errKnown; }
  inline double error() const {
    assert( _errKnown );
    return _err;
  }
 
  double prec() const;
  void   operator=( const EvtValError& other );
  void   operator*=( const EvtValError& other );
  void   operator/=( const EvtValError& other );
  void   operator+=( const EvtValError& other );
  void   operator*=( double c );
 
  void print( std::ostream& ) const;
 
private:
  int    _valKnown;
  double _val;
  int    _errKnown;
  double _err;
};
 
EvtValError operator*( const EvtValError& x1, const EvtValError& x2 );
EvtValError operator/( const EvtValError& x1, const EvtValError& x2 );
EvtValError operator+( const EvtValError& x1, const EvtValError& x2 );
EvtValError operator*( const EvtValError& x, double c );
EvtValError operator*( double c, const EvtValError& x );
 
std::ostream& operator<<( std::ostream&, const EvtValError& );
 
// Perform an accept/reject fraction count
 
template <class InputIterator, class Predicate>
EvtValError accept_reject( InputIterator it, InputIterator end, Predicate pred ) {
  int itsTried  = 0;
  int itsPassed = 0;
  while ( it != end )
  {
 
    itsTried++;
    if ( pred( *it++ ) ) itsPassed++;
  }
 
  return EvtValError( ( (double)itsPassed ) / ( (double)itsTried ),
                      sqrt( itsPassed ) / ( (double)itsTried ) );
}
 
#endif