gsl_inte_qagiu.h

/*
  -------------------------------------------------------------------
  
  Copyright (C) 2006, 2007, 2008, Andrew W. Steiner
  
  This file is part of O2scl.
  
  O2scl 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 3 of the License, or
  (at your option) any later version.
  
  O2scl 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.
  
  You should have received a copy of the GNU General Public License
  along with O2scl. If not, see <http://www.gnu.org/licenses/>.

  -------------------------------------------------------------------
*/
#ifndef O2SCL_GSL_INTE_QAGIU_H
#define O2SCL_GSL_INTE_QAGIU_H

#include <o2scl/inte.h>
#include <o2scl/gsl_inte_qags.h>

#ifndef DOXYGENP
namespace o2scl {
#endif

  /** \brief Integrate a function from \f$ a \f$ to \f$ \infty \f$ 
      (GSL)

      The number of subdivisions of the original interval which 
      this class is allowed to make is dictated by the workspace
      size for the integration class, which can be set using
      \ref gsl_inte_table::set_wkspace() . 
      
      \todo I had to add extra code to check for non-finite
      values for some integrations. This should be checked.
      
      The extra line was of the form:
      \verbatim
      if (!finite(area1)) area1=0.0;
      \endverbatim
  */
  template<class param_t, class func_t=funct<param_t> > class gsl_inte_qagiu : 
  public gsl_inte_transform<param_t,func_t> {
      
#ifndef DOXGYEN_INTERNAL

  protected:

    /// Store the lower limit
    double la;

#endif
      
  public:
    
    /** 
        
    \brief Integrate function \c func from \c a to \f$ \infty \f$

        The value \c b is ignored.
     */
    virtual double integ(func_t &func, double a, double b, param_t &pa) {
      double res, err;
      integ_err(func,a,b,pa,res,err);
      this->interror=err;
      return res;
    }
      
    /** 
        \brief Integrate function \c func from \c a to \f$ \infty \f$ 
        giving result \c res and error \c err

        The value \c b is ignored.
    */
    virtual int integ_err(func_t &func, double a, double b, 
                          param_t &pa, double &res, double &err2) {
        
      la=a;

      double fv1[8], fv2[8];
        
      int status=qags(func,8,o2scl_inte_qag_coeffs::qk15_xgk,
                       o2scl_inte_qag_coeffs::qk15_wg,
                       o2scl_inte_qag_coeffs::qk15_wgk,
                       fv1,fv2,0.0,1.0,this->tolx,this->tolf,
                       this->wkspace,&res,&err2,pa);

      return status;
        
    }

#ifndef DOXYGEN_INTERNAL

  protected:
    
    /// Transform to \f$ t \in (0,1] \f$
    virtual double transform(func_t &func, double t, param_t &pa) {
      double x=la+(1-t)/t, y=0.0;
      func(x,y,pa);
        
      return y/t/t;
    }

#endif
      
  };
  
#ifndef DOXYGENP
}
#endif

#endif

---

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