1 | static double |
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2 | form_volume(double length_a, double length_b, double length_c) |
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3 | { |
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4 | return length_a * length_b * length_c; |
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5 | } |
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6 | |
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7 | |
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8 | static double |
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9 | Iq(double q, |
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10 | double sld, |
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11 | double solvent_sld, |
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12 | double length_a, |
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13 | double length_b, |
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14 | double length_c) |
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15 | { |
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16 | const double mu = 0.5 * q * length_b; |
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17 | |
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18 | // Scale sides by B |
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19 | const double a_scaled = length_a / length_b; |
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20 | const double c_scaled = length_c / length_b; |
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21 | |
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22 | // outer integral (with gauss points), integration limits = 0, 1 |
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23 | double outer_total = 0; //initialize integral |
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24 | |
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25 | for( int i=0; i<76; i++) { |
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26 | const double sigma = 0.5 * ( Gauss76Z[i] + 1.0 ); |
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27 | const double mu_proj = mu * sqrt(1.0-sigma*sigma); |
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28 | |
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29 | // inner integral (with gauss points), integration limits = 0, 1 |
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30 | // corresponding to angles from 0 to pi/2. |
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31 | double inner_total = 0.0; |
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32 | for(int j=0; j<76; j++) { |
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33 | const double uu = 0.5 * ( Gauss76Z[j] + 1.0 ); |
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34 | double sin_uu, cos_uu; |
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35 | SINCOS(M_PI_2*uu, sin_uu, cos_uu); |
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36 | const double si1 = sas_sinx_x(mu_proj * sin_uu * a_scaled); |
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37 | const double si2 = sas_sinx_x(mu_proj * cos_uu); |
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38 | inner_total += Gauss76Wt[j] * square(si1 * si2); |
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39 | } |
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40 | inner_total *= 0.5; |
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41 | |
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42 | const double si = sas_sinx_x(mu * c_scaled * sigma); |
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43 | outer_total += Gauss76Wt[i] * inner_total * si * si; |
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44 | } |
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45 | outer_total *= 0.5; |
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46 | |
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47 | // Multiply by contrast^2 and convert from [1e-12 A-1] to [cm-1] |
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48 | const double V = form_volume(length_a, length_b, length_c); |
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49 | const double drho = (sld-solvent_sld); |
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50 | return 1.0e-4 * square(drho * V) * outer_total; |
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51 | } |
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52 | |
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53 | |
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54 | static double |
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55 | Iqxy(double qa, double qb, double qc, |
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56 | double sld, |
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57 | double solvent_sld, |
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58 | double length_a, |
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59 | double length_b, |
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60 | double length_c) |
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61 | { |
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62 | const double siA = sas_sinx_x(0.5*length_a*qa); |
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63 | const double siB = sas_sinx_x(0.5*length_b*qb); |
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64 | const double siC = sas_sinx_x(0.5*length_c*qc); |
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65 | const double V = form_volume(length_a, length_b, length_c); |
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66 | const double drho = (sld - solvent_sld); |
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67 | const double form = V * drho * siA * siB * siC; |
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68 | // Square and convert from [1e-12 A-1] to [cm-1] |
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69 | return 1.0e-4 * form * form; |
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70 | } |
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