/* integration/util.c
 * 
 * Copyright (C) 1996, 1997, 1998, 1999, 2000 Brian Gough
 * 
 * This program 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 of the License, or (at
 * your option) any later version.
 * 
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

static inline
void update (gsl_integration_workspace * workspace,
                 double a1, double b1, double area1, double error1,
                 double a2, double b2, double area2, double error2);

static inline void
retrieve (const gsl_integration_workspace * workspace, 
          double * a, double * b, double * r, double * e);


static inline
void update (gsl_integration_workspace * workspace,
             double a1, double b1, double area1, double error1,
             double a2, double b2, double area2, double error2)
{
  double * alist = workspace->alist ;
  double * blist = workspace->blist ;
  double * rlist = workspace->rlist ;
  double * elist = workspace->elist ;
  size_t * level = workspace->level ;

  const size_t i_max = workspace->i ;
  const size_t i_new = workspace->size ;

  const size_t new_level = workspace->level[i_max] + 1;

  /* append the newly-created intervals to the list */
  
  if (error2 > error1)
    {
      alist[i_max] = a2;        /* blist[maxerr] is already == b2 */
      rlist[i_max] = area2;
      elist[i_max] = error2;
      level[i_max] = new_level;
      
      alist[i_new] = a1;
      blist[i_new] = b1;
      rlist[i_new] = area1;
      elist[i_new] = error1;
      level[i_new] = new_level;
    }
  else
    {
      blist[i_max] = b1;        /* alist[maxerr] is already == a1 */
      rlist[i_max] = area1;
      elist[i_max] = error1;
      level[i_max] = new_level;
      
      alist[i_new] = a2;
      blist[i_new] = b2;
      rlist[i_new] = area2;
      elist[i_new] = error2;
      level[i_new] = new_level;
    }
  
  workspace->size++;

  if (new_level > workspace->maximum_level)
    {
      workspace->maximum_level = new_level;
    }

  qpsrt (workspace) ;
}

static inline void
retrieve (const gsl_integration_workspace * workspace, 
          double * a, double * b, double * r, double * e)
{
  const size_t i = workspace->i;
  double * alist = workspace->alist;
  double * blist = workspace->blist;
  double * rlist = workspace->rlist;
  double * elist = workspace->elist;

  *a = alist[i] ;
  *b = blist[i] ;
  *r = rlist[i] ;
  *e = elist[i] ;
}

static inline double
sum_results (const gsl_integration_workspace * workspace);

static inline double
sum_results (const gsl_integration_workspace * workspace)
{
  const double * const rlist = workspace->rlist ;
  const size_t n = workspace->size;

  size_t k;
  double result_sum = 0;

  for (k = 0; k < n; k++)
    {
      result_sum += rlist[k];
    }
  
  return result_sum;
}

static inline int
subinterval_too_small (double a1, double a2, double b2);

static inline int
subinterval_too_small (double a1, double a2, double b2)
{
  const double e = GSL_DBL_EPSILON;
  const double u = GSL_DBL_MIN;

  double tmp = (1 + 100 * e) * (fabs (a2) + 1000 * u);

  int status = fabs (a1) <= tmp && fabs (b2) <= tmp;

  return status;
}