Schema_Adams_Bashforth_order_2.cpp

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#include <Schema_Adams_Bashforth_order_2.h>
#include <Equation_base.h>
#include <TRUSTTrav.h>
 
Implemente_instanciable(Schema_Adams_Bashforth_order_2,"Schema_Adams_Bashforth_order_2",Schema_Adams_Bashforth_base);
// XD schema_adams_bashforth_order_2 schema_temps_base schema_adams_bashforth_order_2 INHERITS_BRACE not_set
 
Sortie& Schema_Adams_Bashforth_order_2::printOn(Sortie& s) const
{
  return  Schema_Adams_Bashforth_base::printOn(s);
}
 
Entree& Schema_Adams_Bashforth_order_2::readOn(Entree& s)
{
  return Schema_Adams_Bashforth_base::readOn(s) ;
}
 
////////////////////////////////
//                            //
// Schema characteristics     //
//                            //
////////////////////////////////
 
 
/*! @brief Returns the number of temporal values to keep.
 *
 * Here: n-1, n and n+1, so 3.
 *
 */
int Schema_Adams_Bashforth_order_2::nb_valeurs_temporelles() const
{
  return 3 ;
}
 
/*! @brief Returns the number of time steps strictly beyond which the Adams-Bashforth scheme is applied.
 *
 * Here: we need at least 1 past time, so 0.
 *
 */
inline int Schema_Adams_Bashforth_order_2::nb_pas_dt_seuil() const
{
  return 0 ;
}
 
/*! @brief Returns the number of past temporal values.
 *
 * Here: n-1, so 1.
 *
 */
inline int Schema_Adams_Bashforth_order_2::nb_valeurs_passees() const
{
  return 1 ;
}
 
/////////////////////////////////////////
//                                     //
// End of schema characteristics       //
//                                     //
/////////////////////////////////////////
 
void Schema_Adams_Bashforth_order_2::compute_adams_bashforth_coefficients(double time_step, const DoubleTab& times)
{
  assert(times.size_array() == 3); //past, present and future times, stored in ascending order inside "times" table
 
  if (coefficients().size_array() != 2)
    {
      coefficients().resize(2,RESIZE_OPTIONS::NOCOPY_NOINIT);
    }
 
  double past_time          = times[0];
  double present_time       = times[1];
  double future_time        = times[2];
  double past_time_step     = present_time-past_time;
 
  coefficients()[1] = 1./past_time_step;
  coefficients()[1] *= (future_time+present_time-2*past_time);
  coefficients()[1] *= 0.5;
  assert(coefficients()[1] >= 0.);
 
  coefficients()[0] = 1-coefficients()[1];
  assert(coefficients()[0] <= 1.);
}