include/Geant4/G4CascadeInterpolator.hh

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0025 //
0026 //
0027 // Author:  Michael Kelsey <kelsey@slac.stanford.edu>
0028 //
0029 // Simple linear interpolation class, more lightweight than
0030 // G4PhysicsVector.  Templated on number of X-axis (usually energy)
0031 // bins, constructor takes a C-array of bin edges as input, and an
0032 // optional flag whether to extrapolate (the default) or truncate values
0033 // beyond the bin boundaries.
0034 //
0035 // The interpolation action returns a simple double: the integer part
0036 // is the bin index, and the fractional part is, obviously, the
0037 // fractional part.
0038 //
0039 // 20100803  M. Kelsey -- Add printBins() function for debugging
0040 // 20110923  M. Kelsey -- Add optional ostream& argument to printBins()
0041
0042 #ifndef G4CASCADE_INTERPOLATOR_HH
0043 #define G4CASCADE_INTERPOLATOR_HH
0044
0045 #include "globals.hh"
0046 #include <cfloat>
0047 #include <iosfwd>
0048
0049
0050 template <int NBINS>
0051 class G4CascadeInterpolator {
0052 public:
0053   enum { nBins=NBINS, last=NBINS-1 };
0054
0055   G4CascadeInterpolator(const G4double (&xb)[nBins], G4bool extrapolate=true)
0056     : xBins(xb), doExtrapolation(extrapolate),
0057       lastX(-DBL_MAX), lastVal(-DBL_MAX) {}
0058
0059   virtual ~G4CascadeInterpolator() {}
0060
0061   // Find bin position (index and fraction) from input argument
0062   G4double getBin(const G4double x) const;
0063
0064   // Apply bin position from first input to second (array)
0065   G4double interpolate(const G4double x, const G4double (&yb)[nBins]) const;
0066   G4double interpolate(const G4double (&yb)[nBins]) const;
0067
0068   void printBins(std::ostream& os) const;   // Show bin edges for debugging
0069
0070 private:
0071   const G4double (&xBins)[nBins];
0072   G4bool doExtrapolation;
0073
0074   mutable G4double lastX;       // Buffers to remember previous call
0075   mutable G4double lastVal;
0076 };
0077
0078 // NOTE:  G4 requires template function definitions in .hh file
0079 #include "G4CascadeInterpolator.icc"
0080
0081 #endif  /* G4CASCADE_INTERPOLATOR_HH */