package sansmodels;

public class Sphere extends SANSModel{
 
    private double scale, radius, deltaRho, background;

    //Default constructor
    public Sphere() {
        scale = 1.0;
        radius = 60.0;
        deltaRho = 1.e-6;
        background = 0.00;
        setNumberOfParameters(4);
        String[] parameters = {"Scale", "Radius (A)",
            "Contrast (A-2)", "Background (cm-1)"};
        setParametersText(parameters);
    }

    public Sphere(double inScale, double inRadius, double inDeltaRho,
                  double inBackground) {
        scale = inScale; 
        radius = inRadius; 
        deltaRho = inDeltaRho;
        background = inBackground;
        setNumberOfParameters(4);
        String[] parameters = {"Scale", "Radius (A)",
            "Contrast (A-2)", "Background (cm-1)"};
        setParametersText(parameters);
    }

    public double getFormFactor(double inX) {
        double bes, f, vol, f2, xrad;
        xrad = inX*radius;
        bes = 3.*(Math.sin(xrad) - xrad*Math.cos(xrad))/
              Math.pow(xrad,3.0);
        vol = 4.0*Math.PI/3.0*Math.pow(radius,3.0);
        f = bes*deltaRho;
        f2 = f*f*vol*1.0e8;
        return scale*f2*getStructureFactor().calculate(inX)
            +background;
    }

    public void setParameters(double[] inParameters) {
        scale = inParameters[0];
        radius = inParameters[1];
        deltaRho = inParameters[2];
        background = inParameters[3];
    }
 
    public double[] getParameters() {
        double[] outParameters = new double[4];
        outParameters[0] = scale;
        outParameters[1] = radius;
        outParameters[2] = deltaRho;
        outParameters[3] = background;
        return outParameters;
    }
}