1 | /* LamellarCaille kernel - allows for name changes of passed parameters ... |
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2 | |
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3 | */ |
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4 | |
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5 | double Iq(double qval, |
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6 | double del, |
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7 | double Nlayers, |
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8 | double dd, |
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9 | double Cp, |
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10 | double sld, |
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11 | double solvent_sld); |
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12 | |
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13 | double Iq(double qval, |
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14 | double del, |
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15 | double Nlayers, |
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16 | double dd, |
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17 | double Cp, |
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18 | double sld, |
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19 | double solvent_sld) |
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20 | { |
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21 | double contr,NN; //local variables of coefficient wave |
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22 | double inten,Pq,Sq,alpha,temp,t2; |
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23 | //double dQ, dQDefault, t1, t3; |
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24 | int ii,NNint; |
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25 | // from wikipedia 0.577215664901532860606512090082402431042159335 |
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26 | const double Euler = 0.577215664901533; // Euler's constant, increased sig figs for new models Feb 2015 |
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27 | //dQDefault = 0.0; //[=] 1/A, q-resolution, default value |
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28 | //dQ = dQDefault; // REMOVED UNUSED dQ calculations for new models Feb 2015 |
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29 | |
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30 | NN = trunc(Nlayers); //be sure that NN is an integer |
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31 | |
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32 | contr = sld - solvent_sld; |
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33 | |
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34 | Pq = 2.0*contr*contr/qval/qval*(1.0-cos(qval*del)); |
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35 | |
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36 | NNint = (int)NN; //cast to an integer for the loop |
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37 | ii=0; |
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38 | Sq = 0.0; |
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39 | // the vital "=" in ii<= added March 2015 |
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40 | for(ii=1;ii<=(NNint-1);ii+=1) { |
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41 | |
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42 | //fii = (double)ii; //do I really need to do this? - unused variable, removed 18Feb2015 |
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43 | |
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44 | temp = 0.0; |
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45 | alpha = Cp/4.0/M_PI/M_PI*(log(M_PI*ii) + Euler); |
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46 | //t1 = 2.0*dQ*dQ*dd*dd*alpha; |
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47 | t2 = 2.0*qval*qval*dd*dd*alpha; |
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48 | //t3 = dQ*dQ*dd*dd*ii*ii; |
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49 | |
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50 | temp = 1.0-ii/NN; |
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51 | //temp *= cos(dd*qval*ii/(1.0+t1)); |
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52 | temp *= cos(dd*qval*ii); |
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53 | //temp *= exp(-1.0*(t2 + t3)/(2.0*(1.0+t1)) ); |
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54 | temp *= exp(-t2/2.0 ); |
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55 | //temp /= sqrt(1.0+t1); |
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56 | |
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57 | Sq += temp; |
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58 | } |
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59 | |
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60 | Sq *= 2.0; |
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61 | Sq += 1.0; |
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62 | |
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63 | inten = 2.0*M_PI*Pq*Sq/(dd*qval*qval); |
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64 | |
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65 | inten *= 1.0e-04; // 1/A to 1/cm |
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66 | |
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67 | return(inten); |
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68 | } |
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69 | |
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