G4CascadeInterpolator.hh

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// Author:  Michael Kelsey <kelsey@slac.stanford.edu>
//
// Simple linear interpolation class, more lightweight than
// G4PhysicsVector.  Templated on number of X-axis (usually energy)
// bins, constructor takes a C-array of bin edges as input, and an
// optional flag whether to extrapolate (the default) or truncate values
// beyond the bin boundaries.  
//
// The interpolation action returns a simple double: the integer part
// is the bin index, and the fractional part is, obviously, the
// fractional part.
//
// 20100803  M. Kelsey -- Add printBins() function for debugging
// 20110923  M. Kelsey -- Add optional ostream& argument to printBins()
 
#ifndef G4CASCADE_INTERPOLATOR_HH
#define G4CASCADE_INTERPOLATOR_HH
 
#include "globals.hh"
#include <cfloat>
#include <iosfwd>
 
 
template <int NBINS>
class G4CascadeInterpolator {
public:
  enum { nBins=NBINS, last=NBINS-1 };
 
  G4CascadeInterpolator(const G4double (&xb)[nBins], G4bool extrapolate=true)
    : xBins(xb), doExtrapolation(extrapolate),
      lastX(-DBL_MAX), lastVal(-DBL_MAX) {}
 
  virtual ~G4CascadeInterpolator() {}
 
  // Find bin position (index and fraction) from input argument
  G4double getBin(const G4double x) const;
 
  // Apply bin position from first input to second (array)
  G4double interpolate(const G4double x, const G4double (&yb)[nBins]) const;
  G4double interpolate(const G4double (&yb)[nBins]) const;
 
  void printBins(std::ostream& os) const;   // Show bin edges for debugging
 
private:
  const G4double (&xBins)[nBins];
  G4bool doExtrapolation;
 
  mutable G4double lastX;       // Buffers to remember previous call
  mutable G4double lastVal;
};
 
// NOTE:  G4 requires template function definitions in .hh file
#include "G4CascadeInterpolator.icc"
 
#endif  /* G4CASCADE_INTERPOLATOR_HH */