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我正在尝试做这样的事情。
class ODESolver
{
public:
// Fourth-order Runge-Kutta ODE solver.
static void RungeKutta4(ODE ode, double stepSize)
{
// Define some convenience variables to make the
// code more readable
int j;
int numEqns = ode.getNumberOfEquations();
double s;
double *q;
double *dq1 = new double[numEqns];
double *dq2 = new double[numEqns];
double *dq3 = new double[numEqns];
double *dq4 = new double[numEqns];
// Retrieve the current values of the dependent
// and independent variables.
s = ode.getIndependentVar();
q = ode.getAllIndependentVariables();
dq1 = ode.getRightHandSide(s, q, q, stepSize, 0.0);
dq2 = ode.getRightHandSide(s + 0.5*stepSize, q, dq1, stepSize, 0.5);
dq3 = ode.getRightHandSide(s + 0.5*stepSize, q, dq2, stepSize, 0.5);
dq4 = ode.getRightHandSide(s + stepSize, q, dq3, stepSize, 1.0);
// Update the dependent and independent variable values
// at the new dependent variable location and store the
// values in the ODE object arrays.
ode.setIndependentValue(s + stepSize);
for (j = 0; j < numEqns; j++)
{
q[j] = q[j] + (dq1[j] + 2.0*dq2[j] + 2.0*dq3[j] + dq4[j]) / 6.0;
ode.setDependentValue(q[j], j);
}
}
};
class ODE
{
// Declare fields used by the class
private:
int numEqns; // number of equations to solve
double *dependent; // array of dependent variables
double independent; // independent variable
// Constructor
public :
// Constructor
ODE:: ODE(int numEqns) {
this->numEqns = numEqns;
dependent = new double[numEqns];
virtual double* getRightHandSide(double IndependentVariable, double DependentVariables[],
double DeltaOfDependents[], double DIndependent, double DependentScale);
};
class SimpleProjectile : public ODE {
public:
// Gravitational acceleration.
static double Gravity;
SimpleProjectile::SimpleProjectile(double x0, double y0, double vx0, double vy0,
double t);
// These methods return the location, velocity,
// and time values.
double getVx();
double getVy();
double getX();
double getY();
double getTime();
// This method updates the velocity and position
// of the projectile according to the gravity-only model.
void updateLocationAndVelocity(double dt);
// Because SimpleProjectile extends the ODE class,
// it must implement the getRightHandSide method.
// In this case, the method returns a dummy array.
double* getRightHandSide(double s, double Q[],
double deltaQ[], double ds, double qScale)
};
void SimpleProjectile::updateLocationAndVelocity(double dt)
{
double time = getIndependentVar();
double vx0 = getDependentVar(0);
double x0 = getDependentVar(1);
double vy0 = getDependentVar(2);
double y0 = getDependentVar(3);
// Update the xy locations and the y-component
// of velocity. The x-velocity doesn't change.
double x = x0 + vx0*dt;
double vy = vy0 + Gravity*dt;
double y = y0 + vy0*dt + 0.5*Gravity*dt*dt; // s = S0 + (V0 * t + 1/2 a*t^2)
//Update Time
time = time + dt;
//Load new values into ODE
setIndependentValue(time);
setDependentValue(x, 1);
setDependentValue(y, 4);
setDependentValue(vy, 3);
}
class DragProjectile : public SimpleProjectile {
private :
double mass, area, density, Cd;
public:
DragProjectile::DragProjectile(double x0, double y0,
double vx0, double vy0, double time,
double mass, double area, double density, double Cd);
// These methods return the value of the fields
// declared in this class.
double getMass();
double getArea();
double getDensity();
double getCd();
// This method updates the velocity and location
// of the projectile using a 4th order Runge-Kutta
// solver to integrate the equations of motion.
void updateLocationAndVelocity(double dt);
double* getRightHandSide(double IndependentVariable, double DependentVariables[],
double DeltaOfDependents[], double DIndependent, double IndependentScale);
};
void DragProjectile::updateLocationAndVelocity(double dt)
{
ODESolver::RungeKutta4(this, dt); // this is where problem comes in
}
现在我想将 ODESolver::RungeKutta4 中的 DragProjectile 作为 ODE 对象传递，因为它的派生类 SimpleMotion 和 SimpleMotion 派生自 ODE 类。 我试过向上转换，但找不到关键字的解决方法:“this”