libclhep-dev 2.1.4.1-1.2 / usr / include / CLHEP / GenericFunctions / ButcherTableau.icc

namespace Genfun {
  ButcherTableau::ButcherTableau(const std::string &xname, unsigned int xorder):_name(xname),_order(xorder){
  }
  
  
  const std::string & ButcherTableau::name() const {
    return _name;
  }
  
  
  
  unsigned int ButcherTableau::order() const{
    return _order;
  }
  
  
  
  unsigned int ButcherTableau::nSteps() const{
    return _A.size();
  }

// don't generate warnings about intentional shadowing
#if defined __GNUC__ 
  #if __GNUC__ > 3 && __GNUC_MINOR__ > 6
    #pragma GCC diagnostic push
    #pragma GCC diagnostic ignored "-Wshadow"
  #endif
#endif 
#ifdef __clang__
  #pragma clang diagnostic push
  #pragma clang diagnostic ignored "-Wshadow"
#endif

  double & ButcherTableau::A(unsigned int i, unsigned int j) {
    
    if (i>=_A.size()) {
      unsigned int newSize=i+1; // (shadowed)
      for (unsigned int ii=0;ii<_A.size();ii++) {
	_A[ii].resize(newSize,0.0);
      }
      for (unsigned int ii=_A.size();ii<newSize;ii++) {
	_A.push_back(std::vector<double>(newSize,0));
      }
      
      if (j>=_A[i].size()) {
	unsigned int newSize=j+1;  // (shadow)
	for (unsigned int ii=0;ii<_A.size();ii++) {
	  _A[ii].resize(newSize,0.0);
	}
      }
    }
    return _A[i][j];
  }
  
#if defined __GNUC__ 
  #if __GNUC__ > 3 && __GNUC_MINOR__ > 6
    #pragma GCC diagnostic pop
  #endif
#endif 
#ifdef __clang__
  #pragma clang diagnostic pop
#endif

  double & ButcherTableau::b(unsigned int i){
    if (i>=_b.size()) _b.resize(i+1);
    return _b[i];
  }

  double & ButcherTableau::c(unsigned int i){
    if (i>=_c.size()) _c.resize(i+1);
    return _c[i];
  }
  
  const double & ButcherTableau::A(unsigned int i, unsigned int j) const{
    return _A[i][j];
  }
  
  const double & ButcherTableau::b(unsigned int i) const{
    return _b[i];
  }
  
  const double & ButcherTableau::c(unsigned int i) const{
    return _c[i];
  }
}

std::ostream & operator << (std::ostream & o, const Genfun::ButcherTableau & b) {
  o << "Name " << b.name() << " of order " << b.order() << std::endl;
  o << "A" << std::endl;
  for (unsigned int i=0;i<b.nSteps();i++) {
    for (unsigned int j=0;j<b.nSteps();j++) {
      o << b.A(i,j) << " ";
    }
    o << std::endl;
  }
  o<< std::endl;
  o << "c" << std::endl;
  for (unsigned int j=0;j<b.nSteps();j++) {
    o << b.c(j) << std::endl;
  }
  o<< std::endl;
  o << "b" << std::endl;
  for (unsigned int j=0;j<b.nSteps();j++) {
    o << b.b(j) << " ";
  }
  o << std::endl;
  return o;
}

namespace Genfun {
  EulerTableau::EulerTableau():
    ButcherTableau("Euler Method", 1)
  {
    A(0,0)=0;
    b(0)=1;
    c(0)=1;
  }

  MidpointTableau::MidpointTableau():
    ButcherTableau("Midpoint Method", 2)
  {
    A(1,0)=1/2.0;
    c(0)=0;
    c(1)=1/2.0;
    b(0)=0;
    b(1)=1;
    
  }

  TrapezoidTableau::TrapezoidTableau():
    ButcherTableau("Trapezoid Method", 2)
  {
    A(1,0)=1;
    c(0)=0;
    c(1)=1;
    b(0)=1/2.0;
    b(1)=1/2.0;

  }

  RK31Tableau::RK31Tableau():
    ButcherTableau("RK31 Method", 3)
  {
    A(0,0)      ;    A(0,1)      ;   A(0,2);
    A(1,0)=2/3.0;    A(1,1)      ;   A(1,2);
    A(2,0)=1/3.0;    A(2,1)=1/3.0;   A(2,2);

    c(0)=0;
    c(1)=2/3.0;
    c(2)=2/3.0;
    b(0)=1/4.0;
    b(1)=0;
    b(2)=3/4.0;
  }


  RK32Tableau::RK32Tableau():
    ButcherTableau("RK32 Method", 3)
  {
    A(0,0)      ;    A(0,1)      ;   A(0,2);
    A(1,0)=1/2.0;    A(1,1)      ;   A(1,2);
    A(2,0)=-1   ;    A(2,1)= 2   ;   A(2,2);

    c(0)=0;
    c(1)=1/2.0;
    c(2)=1;
    b(0)=1/6.0;
    b(1)=2/3.0;
    b(2)=1/6.0;

  }

  ClassicalRungeKuttaTableau::ClassicalRungeKuttaTableau():
    ButcherTableau("Classical Runge Kutta Method", 4)
  {
    A(0,0)      ;    A(0,1)       ;   A(0,2)    ; A(0,3);
    A(1,0)=1/2.0;    A(1,1)       ;   A(1,2)    ; A(1,3);
    A(2,0)=0    ;    A(2,1)=1/2.0 ;   A(2,2)    ; A(2,3);
    A(3,0)=0    ;    A(3,1)=0     ;   A(3,2)=1  ; A(3,3);

    c(0)=0;
    c(1)=1/2.0;
    c(2)=1/2.0;
    c(3)=1;
    b(0)=1/6.0;
    b(1)=1/3.0;
    b(2)=1/3.0;
    b(3)=1/6.0;
  }

  ThreeEighthsRuleTableau::ThreeEighthsRuleTableau():
    ButcherTableau("Three-Eighths Rule Method", 4)
  {
    A(0,0)        ;    A(0,1)       ;   A(0,2)    ; A(0,3);
    A(1,0)=1/3.0  ;    A(1,1)       ;   A(1,2)    ; A(1,3);
    A(2,0)=-1/3.0 ;    A(2,1)=1     ;   A(2,2)    ; A(2,3);
    A(3,0)=1      ;    A(3,1)=-1    ;   A(3,2)=1  ; A(3,3);

    c(0)=0;
    c(1)=1/3.0;
    c(2)=2/3.0;
    c(3)=1;
    b(0)=1/8.0;
    b(1)=3/8.0;
    b(2)=3/8.0;
    b(3)=1/8.0;
  }
}