public TrajectoryDeterminationProblem(double t0,
double x0Guess, double y0Guess,
double vx0Guess, double vy0Guess) {
this.t0 = t0;
x0 = new EstimatedParameter( "x0", x0Guess);
y0 = new EstimatedParameter( "y0", y0Guess);
vx0 = new EstimatedParameter("vx0", vx0Guess);
vy0 = new EstimatedParameter("vy0", vy0Guess);
// inform the base class about the parameters
addParameter(x0);
addParameter(y0);
addParameter(vx0);