gsl_inte.h

00001 /*
00002   -------------------------------------------------------------------
00003   
00004   Copyright (C) 2006, 2007, Andrew W. Steiner
00005   
00006   This file is part of O2scl.
00007   
00008   O2scl is free software; you can redistribute it and/or modify
00009   it under the terms of the GNU General Public License as published by
00010   the Free Software Foundation; either version 3 of the License, or
00011   (at your option) any later version.
00012   
00013   O2scl is distributed in the hope that it will be useful,
00014   but WITHOUT ANY WARRANTY; without even the implied warranty of
00015   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00016   GNU General Public License for more details.
00017   
00018   You should have received a copy of the GNU General Public License
00019   along with O2scl. If not, see <http://www.gnu.org/licenses/>.
00020 
00021   -------------------------------------------------------------------
00022 */
00023 #ifndef O2SCL_GSL_INTE_H
00024 #define O2SCL_GSL_INTE_H
00025 
00026 #include <gsl/gsl_machine.h>
00027 
00028 #ifndef DOXYGENP
00029 namespace o2scl {
00030 #endif
00031   
00032   /** 
00033       \brief GSL integration base
00034 
00035       This base class does not perform any actual integration. 
00036 
00037   */
00038   class gsl_inte {
00039     
00040   public:
00041 
00042     gsl_inte() {
00043     }
00044     
00045   protected:
00046 
00047     /**
00048        \brief Rescale errors appropriately
00049     */
00050     double rescale_error(double err, const double result_abs, 
00051                          const double result_asc) {
00052       err = fabs(err);
00053       
00054       if (result_asc != 0 && err != 0) {
00055         
00056         double scale = pow((200 * err / result_asc), 1.5);
00057         
00058         if (scale < 1) {
00059           err = result_asc * scale;
00060         } else {
00061           err = result_asc;
00062         }
00063       }
00064 
00065       if (result_abs > GSL_DBL_MIN / (50 * GSL_DBL_EPSILON)) {
00066 
00067         double min_err = 50 * GSL_DBL_EPSILON * result_abs;
00068         
00069         if (min_err > err) {
00070           err = min_err;
00071         }
00072       }
00073       
00074       return err;
00075     }
00076     
00077   };
00078   
00079   
00080 #ifndef DOXYGENP
00081 }
00082 #endif
00083 
00084 #endif

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