GSLInterpolator.h

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// @(#)root/mathmore:$Id$
// Authors: L. Moneta, A. Zsenei   08/2005

 /**********************************************************************
  *                                                                    *
  * Copyright (c) 2004 ROOT Foundation,  CERN/PH-SFT                   *
  *                                                                    *
  * This library is free software; you can redistribute it and/or      *
  * modify it under the terms of the GNU General Public License        *
  * as published by the Free Software Foundation; either version 2     *
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  * This library is distributed in the hope that it will be useful,    *
  * but WITHOUT ANY WARRANTY; without even the implied warranty of     *
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU   *
  * General Public License for more details.                           *
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  * You should have received a copy of the GNU General Public License  *
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  * 330, Boston, MA 02111-1307 USA, or contact the author.             *
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  **********************************************************************/

// Header file for class GSLInterpolator
//
// Created by: moneta  at Fri Nov 26 15:31:41 2004
//
// Last update: Fri Nov 26 15:31:41 2004
//
#ifndef ROOT_Math_GSLInterpolator
#define ROOT_Math_GSLInterpolator

#include <vector>
#include <string>
#include <cassert>

#include "Math/InterpolationTypes.h"

#include "gsl/gsl_interp.h"
#include "gsl/gsl_spline.h"

#include "gsl/gsl_errno.h"
#include "Math/Error.h"

namespace ROOT {
namespace Math {


   /**
   Interpolation class based on GSL interpolation functions
    @ingroup Interpolation
    */

   class GSLInterpolator {

   public:

      GSLInterpolator(unsigned int ndata, Interpolation::Type type);

      GSLInterpolator(const Interpolation::Type type, const std::vector<double> & x, const std::vector<double> & y );
      virtual ~GSLInterpolator();

   private:
      // usually copying is non trivial, so we make this unaccessible
      GSLInterpolator(const GSLInterpolator &);
      GSLInterpolator & operator = (const GSLInterpolator &);

   public:

      bool Init(unsigned int ndata, const double *x, const double *y);

      double Eval(double x) const
      {
         assert(fAccel);
         double y = 0;
         static unsigned int nErrors = 0;
         int ierr = gsl_spline_eval_e(fSpline, x, fAccel, &y);

         if (fResetNErrors)
           nErrors = 0, fResetNErrors = false;

         if (ierr) {
            ++nErrors;
            if(nErrors <= 4) {
               MATH_WARN_MSG("GSLInterpolator::Eval", gsl_strerror(ierr));
               if(nErrors == 4)
                  MATH_WARN_MSG("GSLInterpolator::Eval", "Suppressing additional warnings");
            }
         }

         return y;
      }

      double Deriv(double x) const
      {
         assert(fAccel);
         double deriv = 0;
         static unsigned int nErrors = 0;
         int ierr = gsl_spline_eval_deriv_e(fSpline, x, fAccel, &deriv);

         if (fResetNErrors)
           nErrors = 0, fResetNErrors = false;

         if (ierr) {
            ++nErrors;
            if(nErrors <= 4) {
               MATH_WARN_MSG("GSLInterpolator::Deriv", gsl_strerror(ierr));
               if(nErrors == 4)
                  MATH_WARN_MSG("GSLInterpolator::Deriv", "Suppressing additional warnings");
            }
         }

         return deriv;
      }

      double Deriv2(double x) const {
         assert(fAccel);
         double deriv2 = 0;
         static unsigned int nErrors = 0;
         int ierr = gsl_spline_eval_deriv2_e(fSpline, x, fAccel, &deriv2);

         if (fResetNErrors)
           nErrors = 0, fResetNErrors = false;

         if (ierr) {
            ++nErrors;
            if(nErrors <= 4) {
               MATH_WARN_MSG("GSLInterpolator::Deriv2", gsl_strerror(ierr));
               if(nErrors == 4)
                  MATH_WARN_MSG("GSLInterpolator::Deriv2", "Suppressing additional warnings");
            }
         }

         return deriv2;
      }

      double Integ(double a, double b) const {
         if (a > b) // gsl will report an error in this case
           return -Integ(b, a);

         assert(fAccel);
         double result = 0;
         static unsigned int nErrors = 0;
         int ierr = gsl_spline_eval_integ_e(fSpline, a, b, fAccel, &result);

         if (fResetNErrors)
           nErrors = 0, fResetNErrors = false;

         if (ierr) {
            ++nErrors;
            if(nErrors <= 4) {
               MATH_WARN_MSG("GSLInterpolator::Integ", gsl_strerror(ierr));
               if(nErrors == 4)
                  MATH_WARN_MSG("GSLInterpolator::Integ", "Suppressing additional warnings");
            }
         }

         return result;
      }

      std::string Name() {
         return fInterpType->name;
      }

   private:

      mutable bool fResetNErrors;  // flag to reset counter for error messages
      gsl_interp_accel * fAccel;
      gsl_spline * fSpline;
      const gsl_interp_type * fInterpType;

   };

} // namespace Math
} // namespace ROOT

#endif /* ROOT_Math_GSLInterpolator */