1 | double form_volume(double radius, double length); |
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2 | double Iq(double q, double sld, double solvent_sld, double radius, double length); |
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3 | double Iqxy(double qx, double qy, double sld, double solvent_sld, |
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4 | double radius, double length, double theta, double phi); |
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5 | |
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6 | #define INVALID(v) (v.radius<0 || v.length<0) |
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7 | |
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8 | double form_volume(double radius, double length) |
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9 | { |
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10 | return M_PI*radius*radius*length; |
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11 | } |
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12 | |
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13 | double Iq(double q, |
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14 | double sld, |
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15 | double solvent_sld, |
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16 | double radius, |
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17 | double length) |
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18 | { |
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19 | // precompute qr and qh to save time in the loop |
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20 | const double qr = q*radius; |
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21 | const double qh = q*0.5*length; |
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22 | |
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23 | // translate a point in [-1,1] to a point in [0, pi/2] |
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24 | const double zm = M_PI_4; |
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25 | const double zb = M_PI_4; |
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26 | |
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27 | double total = 0.0; |
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28 | for (int i=0; i<76 ;i++) { |
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29 | const double alpha = Gauss76Z[i]*zm + zb; |
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30 | double sn, cn; |
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31 | SINCOS(alpha, sn, cn); |
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32 | const double fq = sinc(qh*cn) * sas_J1c(qr*sn); |
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33 | total += Gauss76Wt[i] * fq*fq * sn; |
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34 | } |
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35 | // translate dx in [-1,1] to dx in [lower,upper] |
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36 | const double form = total*zm; |
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37 | const double s = (sld - solvent_sld) * form_volume(radius, length); |
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38 | return 1.0e-4 * s * s * form; |
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39 | } |
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40 | |
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41 | |
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42 | double Iqxy(double qx, double qy, |
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43 | double sld, |
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44 | double solvent_sld, |
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45 | double radius, |
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46 | double length, |
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47 | double theta, |
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48 | double phi) |
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49 | { |
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50 | double sn, cn; // slots to hold sincos function output |
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51 | |
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52 | // Compute angle alpha between q and the cylinder axis |
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53 | SINCOS(theta*M_PI_180, sn, cn); |
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54 | const double q = sqrt(qx*qx + qy*qy); |
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55 | const double cos_val = (q==0. ? 1.0 : (cn*cos(phi*M_PI_180)*qx + sn*qy)/q); |
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56 | const double alpha = acos(cos_val); |
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57 | |
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58 | SINCOS(alpha, sn, cn); |
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59 | const double fq = sinc(q*0.5*length*cn) * sas_J1c(q*radius*sn); |
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60 | const double s = (sld-solvent_sld) * form_volume(radius, length); |
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61 | return 1.0e-4 * square(s * fq); |
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62 | } |
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