[dc02af0] | 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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[2e35a40] | 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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[dc02af0] | 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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