package sansmodels;

public class CoreShellCylinder extends SANSModel{
 
    private double scale, coreRadius, thickness, background;
    private double rhoCore, rhoShell, rhoSolvent, coreLength;

    //Default constructor
    public CoreShellCylinder() {
        scale = 1.0;
        coreRadius = 20.0;
        thickness = 10.0;
        coreLength = 400.0;
        rhoCore = 1.e-6;
        rhoShell = 4.e-6;
        rhoSolvent = 1.e-6;
        background = 0.00;
        setNumberOfParameters(8);
        String[] parameters = {"Scale", "Core Radius (A)",
            "Shell Thickness (A)", "Core Length (A)",
            "Core SLD (A-2)", "Shell SLD (A-2)",
            "Solvent SLD (A-2)", "Background (cm-1)"};
        setParametersText(parameters);
    }

    public CoreShellCylinder(double inScale, 
                     double inCoreRadius,
                     double inThickness,
                     double inCoreLength,
                     double inRhoCore,
                     double inRhoShell,
                     double inRhoSolvent,
                     double inBackground) {
        scale = inScale; 
        coreRadius = inCoreRadius;
        thickness = inThickness;
        coreLength = inCoreLength;
        rhoCore = inRhoCore;
        rhoShell = inRhoShell;
        rhoSolvent = inRhoSolvent;
        background = inBackground;
        setNumberOfParameters(8);
        String[] parameters = {"Scale", "Core Radius (A)",
            "Shell Thickness (A)", "Core Length (A)",
            "Core SLD (A-2)", "Shell SLD (A-2)",
            "Solvent SLD (A-2)", "Background (cm-1)"};
        setParametersText(parameters);
    }

    private double coreShellCylinderFunc(double inQ, double inZ) {
        double dr1, dr2, bessarg1, bessarg2, vol1, vol2;
        double sinarg1, sinarg2, t1, t2, retval;
        
        dr1 = rhoCore - rhoShell;
        dr2 = rhoShell - rhoSolvent;
        vol1 = Math.PI*coreRadius*coreRadius*coreLength;
        vol2 = Math.PI*(coreRadius + thickness) *(coreRadius + thickness)
               *(coreLength+2.0*thickness);
        bessarg1 = inQ*coreRadius*Math.sin(inZ);
        bessarg2 = inQ*(coreRadius+thickness)*Math.sin(inZ);
        sinarg1 = inQ*(coreLength/2.0)*Math.cos(inZ);
        sinarg2 = inQ*(coreLength/2.0 + thickness)*Math.cos(inZ);
        t1 = 2.0*vol1*dr1*Math.sin(sinarg1)/sinarg1
             *SpecialFunction.j1(bessarg1)/bessarg1;
        t2 = 2.0*vol2*dr2*Math.sin(sinarg2)/sinarg2
             *SpecialFunction.j1(bessarg2)/bessarg2;
        return (t1+t2)*(t1+t2)*Math.sin(inZ);
    }
 
    public double getFormFactor(double inX) {

        int nord = 76;
        double va, vb, summ, zi, answer, yyy;
        double vol;
        va = 0.0;
        vb = Math.PI/2.0;
        

        summ = 0.0;
        
        for(int i=0;i<nord;i++) {
            zi = (Gaussian.z76[i]*(vb-va) + vb + va)/2.0;
            yyy = Gaussian.w76[i]*coreShellCylinderFunc(inX,zi);
            summ += yyy;
        }
         
        answer = (vb-va)/2.0*summ;
        
        vol = Math.PI*(coreRadius+thickness)*(coreRadius+thickness)
              *(coreLength+2*thickness);
        return answer/vol*1.0e8*scale*getStructureFactor().calculate(inX) 
            + background;
    }

    public void setParameters(double[] inParameters) {
        scale = inParameters[0];
        coreRadius = inParameters[1];
        thickness = inParameters[2];
        coreLength = inParameters[3];
        rhoCore = inParameters[4];
        rhoShell = inParameters[5];
        rhoSolvent = inParameters[6];
        background = inParameters[7];
    }
 
    public double[] getParameters() {
        double[] outParameters = new double[8];
        outParameters[0] = scale;
        outParameters[1] = coreRadius;
        outParameters[2] = thickness;
        outParameters[3] = coreLength;
        outParameters[4] = rhoCore;
        outParameters[5] = rhoShell;
        outParameters[6] = rhoSolvent;
        outParameters[7] = background;
        return outParameters;
    }
}