SolveRiemannProblem.py

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# This file is part of the ExaHyPE2 project. For conditions of distribution and 
# use, please see the copyright notice at www.peano-framework.org
 
from .AbstractRungeKuttaDGActionSet import AbstractRungeKuttaDGActionSet
 
from exahype2.solvers.ButcherTableau import ButcherTableau
 
import peano4
import jinja2
 
 
class SolveRiemannProblem(AbstractRungeKuttaDGActionSet):
  """
  Solve the actual Riemann problem and add stuff back to the solution.
 
  See the discussion of RungeKuttaDG for a discussion regarding the individual
  steps.
  """
 
  TemplateProject = """
  {% for PREDICATE_NO in range(0,PREDICATES|length) %}
  if ({{PREDICATES[PREDICATE_NO]}}) {
    // no support for local time stepping or subcycling
    /*
    assertionNumericalEquals2(
      {{FACE_METADATA_ACCESSOR}}.getOldTimeStamp(0),
      {{FACE_METADATA_ACCESSOR}}.getOldTimeStamp(1),
      {{FACE_METADATA_ACCESSOR}}.toString(),
      marker.toString()
    );
    */
 
    // Doesn't make a difference if we pick left or right
    const double timeStampOldSolution = {{FACE_METADATA_ACCESSOR}}.getOldTimeStamp(0);
 
    // Set the variable
    // double timeStepSize
    {{COMPUTE_TIME_STEP_SIZE}}
 
    const double timeStamp = timeStampOldSolution + {{BUTCHER_TABLEAU_RELATIVE_TIME_STEP_SIZES[PREDICATE_NO]}} * timeStepSize;
 
    assertion5( tarch::la::greaterEquals( timeStepSize, 0.0 ),  timeStamp, timeStepSize, timeStampOldSolution, {{FACE_METADATA_ACCESSOR}}.toString(), marker.toString() );
    assertion5( tarch::la::greaterEquals( timeStamp, 0.0 ),     timeStamp, timeStepSize, timeStampOldSolution, {{FACE_METADATA_ACCESSOR}}.toString(), marker.toString() );
 
    const double* __restrict__ QIn  = fineGridFace{{UNKNOWN_IDENTIFIER}}EstimateProjection.value;
    double* __restrict__       QOut = fineGridFace{{UNKNOWN_IDENTIFIER}}RiemannSolution.value;
 
    ::exahype2::dg::{{KERNEL_NAMESPACE}}::{{RIEMANN_COMPUTE_KERNEL_CALL}}
  }
  {% endfor %}
"""
 
 
  def __init__(self,solver):
    """
    guard_project: String (C++ code)
      Predicate which controls if the solution is actually projected.
 
    guard_safe_old_time_step: String (C++ code)
      Predicate which controls if the projection should be copied into
      the old solution and the time step should also be moved over.
    """
    super(SolveRiemannProblem,self).__init__(solver)
    self.guardsguardsguards            = []
    self._butcher_tableau     = ButcherTableau(self._solver._rk_order)
 
 
  @property
  def guards(self):
    if self._guards==[]:
      raise Exception("Guards are not initialised")
    return self._guards
 
 
  @guards.setter
  def guards(self,new_guards):
    if new_guards!=[] and len(new_guards)!=self._solver.number_of_Runge_Kutta_steps():
      raise Exception( "Expect one guard per Runge Kutta step. Have {} steps but got guards {}".format(solver.number_of_Runge_Kutta_steps(),guards) )
    self._guards = new_guards
 
 
  def get_body_of_operation(self,operation_name):
    result = ""
    if operation_name==peano4.solversteps.ActionSet.OPERATION_TOUCH_FACE_FIRST_TIME:
      d = {}
      self._solver._init_dictionary_with_default_parameters(d)
      self._solver.add_entries_to_text_replacement_dictionary(d)
      d[ "PREDICATES" ]            = self.guardsguardsguards
      d[ "BUTCHER_TABLEAU_RELATIVE_TIME_STEP_SIZES" ] = self._butcher_tableau.time_step_sizes()
      d[ "FACE_METADATA_ACCESSOR" ] = "fineGridFace"  + self._solver._face_label.name
      result = jinja2.Template(self.TemplateProject).render(**d)
      pass
    return result
 
 
  def get_action_set_name(self):
    return __name__.replace(".py", "").replace(".", "_")
 
 
  def get_includes(self):
    return super(SolveRiemannProblem,self).get_includes() + """
#include "exahype2/dg/rusanov/Rusanov.h"
    """