source: sasview/sansmodels/src/sans/models/c_models/sc.cpp @ 30ccad1

/**
        This software was developed by the University of Tennessee as part of the
        Distributed Data Analysis of Neutron Scattering Experiments (DANSE)
        project funded by the US National Science Foundation.

        If you use DANSE applications to do scientific research that leads to
        publication, we ask that you acknowledge the use of the software with the
        following sentence:

        "This work benefited from DANSE software developed under NSF award DMR-0520547."

        copyright 2008, University of Tennessee
 */

/**
 * Scattering model classes
 * The classes use the IGOR library found in
 *   sansmodels/src/libigor
 *
 */

#include <math.h>
#include "models.hh"
#include "parameters.hh"
#include <stdio.h>
using namespace std;

extern "C" {
        #include "libSphere.h"
        #include "sc.h"
}

SCCrystalModel :: SCCrystalModel() {
        scale      = Parameter(1.0);
        dnn             = Parameter(220.0);
        d_factor = Parameter(0.06);
        radius     = Parameter(40.0, true);
        radius.set_min(0.0);
        sldSph   = Parameter(3.0e-6);
        sldSolv   = Parameter(6.3e-6);
        background = Parameter(0.0);
        theta  = Parameter(0.0, true);
        phi    = Parameter(0.0, true);
        psi    = Parameter(0.0, true);
}

/**
 * Function to evaluate 1D scattering function
 * The NIST IGOR library is used for the actual calculation.
 * @param q: q-value
 * @return: function value
 */
double SCCrystalModel :: operator()(double q) {
        double dp[7];

        // Fill parameter array for IGOR library
        // Add the background after averaging
        dp[0] = scale();
        dp[1] = dnn();
        dp[2] = d_factor();
        dp[3] = radius();
        dp[4] = sldSph();
        dp[5] = sldSolv();
        dp[6] = 0.0;

        // Get the dispersion points for the radius
        vector<WeightPoint> weights_rad;
        radius.get_weights(weights_rad);

        // Perform the computation, with all weight points
        double sum = 0.0;
        double norm = 0.0;
        double vol = 0.0;
        double result;

        // Loop over radius weight points
        for(int i=0; i<weights_rad.size(); i++) {
                dp[3] = weights_rad[i].value;

                //Un-normalize SphereForm by volume
                result = SC_ParaCrystal(dp, q) * pow(weights_rad[i].value,3);
                // This FIXES a singualrity the kernel in libigor.
                if ( result == INFINITY || result == NAN){
                        result = 0.0;
                }
                sum += weights_rad[i].weight
                        * result;
                //Find average volume
                vol += weights_rad[i].weight
                        * pow(weights_rad[i].value,3);

                norm += weights_rad[i].weight;
        }

        if (vol != 0.0 && norm != 0.0) {
                //Re-normalize by avg volume
                sum = sum/(vol/norm);}
        return sum/norm + background();
}

/**
 * Function to evaluate 2D scattering function
 * @param q_x: value of Q along x
 * @param q_y: value of Q along y
 * @return: function value
 */
double SCCrystalModel :: operator()(double qx, double qy) {
        SCParameters dp;
        double q = sqrt(qx*qx + qy*qy);
        dp.scale      = scale();
        dp.dnn   = dnn();
        dp.d_factor   = d_factor();
        dp.radius  = radius();
        dp.sldSph   = sldSph();
        dp.sldSolv   = sldSolv();
        dp.background = 0.0;
        dp.theta  = theta();
        dp.phi    = phi();
        dp.psi    = psi();

        // Get the dispersion points for the radius
        vector<WeightPoint> weights_rad;
        radius.get_weights(weights_rad);

        // Get angular averaging for theta
        vector<WeightPoint> weights_theta;
        theta.get_weights(weights_theta);

        // Get angular averaging for phi
        vector<WeightPoint> weights_phi;
        phi.get_weights(weights_phi);

        // Get angular averaging for psi
        vector<WeightPoint> weights_psi;
        psi.get_weights(weights_psi);

        // Perform the computation, with all weight points
        double sum = 0.0;
        double norm = 0.0;
        double norm_vol = 0.0;
        double vol = 0.0;
        double pi = 4.0*atan(1.0);
        // Loop over radius weight points
        for(int i=0; i<weights_rad.size(); i++) {
                dp.radius = weights_rad[i].value;
                // Average over theta distribution
                for(int j=0; j< weights_theta.size(); j++) {
                        dp.theta = weights_theta[j].value;
                        // Average over phi distribution
                        for(int k=0; k< weights_phi.size(); k++) {
                                dp.phi = weights_phi[k].value;
                                // Average over phi distribution
                                for(int l=0; l< weights_psi.size(); l++) {
                                        dp.psi = weights_psi[l].value;
                                        //Un-normalize SphereForm by volume
                                        double _ptvalue = weights_rad[i].weight
                                                                                * weights_theta[j].weight
                                                                                * weights_phi[k].weight
                                                                                * weights_psi[l].weight
                                                                                * sc_analytical_2DXY(&dp, qx, qy);
                                                                                //* pow(weights_rad[i].value,3.0);
                                        // Consider when there is infinte or nan.
                                        if ( _ptvalue == INFINITY || _ptvalue == NAN){
                                                _ptvalue = 0.0;
                                        }
                                        if (weights_theta.size()>1) {
                                                _ptvalue *= fabs(sin(weights_theta[j].value*pi/180.0));
                                        }
                                        sum += _ptvalue;
                                        // This model dose not need the volume of spheres correction!!!
                                        //Find average volume
                                        //vol += weights_rad[i].weight
                                        //      * pow(weights_rad[i].value,3);
                                        //Find norm for volume
                                        //norm_vol += weights_rad[i].weight;

                                        norm += weights_rad[i].weight
                                                        * weights_theta[j].weight
                                                        * weights_phi[k].weight
                                                        * weights_psi[l].weight;
                                }
                        }
                }
        }
        // Averaging in theta needs an extra normalization
        // factor to account for the sin(theta) term in the
        // integration (see documentation).
        if (weights_theta.size()>1) norm = norm / asin(1.0);

        if (vol != 0.0 && norm_vol != 0.0) {
                //Re-normalize by avg volume
                sum = sum/(vol/norm_vol);}

        return sum/norm + background();
}

/**
 * Function to evaluate 2D scattering function
 * @param pars: parameters of the SCCrystal
 * @param q: q-value
 * @param phi: angle phi
 * @return: function value
 */
double SCCrystalModel :: evaluate_rphi(double q, double phi) {
        return (*this).operator()(q);
}

/**
 * Function to calculate effective radius
 * @return: effective radius value
 */
double SCCrystalModel :: calculate_ER() {
        //NOT implemented yet!!!
}