curveFitter.addObservedPoint( 62, 17586);
curveFitter.addObservedPoint(125, 30582);
curveFitter.addObservedPoint(250, 45087);
curveFitter.addObservedPoint(500, 50683);
ParametricUnivariateFunction f = new ParametricUnivariateFunction() {
public double value(double x, double ... parameters) {
double a = parameters[0];
double b = parameters[1];
double c = parameters[2];
double d = parameters[3];