1 | #include <math.h> |
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2 | #define rr_a (*po) |
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3 | #define rr_d (*(po + 3)) |
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4 | #define eps (2.2204e-016) |
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5 | |
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6 | #include "mex.h" |
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7 | #include "matrix.h" |
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8 | |
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9 | |
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10 | void mexFunction( int dstN, mxArray **aDstP, int aSrcN, const mxArray **aSrcP ) |
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11 | { |
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12 | |
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13 | double *po = mxGetPr(aSrcP[0]); |
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14 | |
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15 | double b,c, b2, bt, v, pit, e, *r; |
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16 | double p, q, D, A, cosphi, phit, R, _2R; |
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17 | |
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18 | b = *(po + 1) / rr_a; |
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19 | c = *(po + 2) / rr_a; |
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20 | b2 = b*b; |
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21 | bt = b/3; |
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22 | |
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23 | p = (3*c - b2)/ 9; |
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24 | q = ((2 * b2 * b)/27 - b*c/3 + rr_d/rr_a) / 2; |
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25 | |
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26 | D = q*q + p*p*p; |
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27 | |
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28 | if (D > 0) |
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29 | { |
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30 | aDstP[0] = mxCreateDoubleMatrix( 1, 1, mxREAL ); |
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31 | r = mxGetPr(aDstP[0]); |
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32 | |
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33 | A = sqrt(D) - q; |
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34 | if (A > 0) |
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35 | { |
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36 | v = pow(A,1.0/3); |
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37 | *r = v - p/v - bt; |
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38 | } else |
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39 | { |
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40 | v = pow(-A,1.0/3); |
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41 | *r = p/v - v - bt; |
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42 | } |
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43 | } else |
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44 | { |
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45 | /* if (p > -eps) |
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46 | { |
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47 | printf("%.17f\n", p); |
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48 | aDstP[0] = mxCreateDoubleMatrix( 1, 1, mxREAL ); |
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49 | r = mxGetPr(aDstP[0]); |
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50 | *r = pow(q,1.0/3) - bt; |
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51 | } |
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52 | else */ |
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53 | { |
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54 | |
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55 | aDstP[0] = mxCreateDoubleMatrix( 3, 1, mxREAL ); |
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56 | r = mxGetPr(aDstP[0]); |
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57 | if (q > 0) e = 1; else e = -1; |
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58 | R = e * sqrt(-p); |
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59 | _2R = R *2; |
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60 | cosphi = q / (R*R*R); |
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61 | if (cosphi > 1) cosphi = 1; else |
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62 | if (cosphi < -1) cosphi = -1; |
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63 | phit = acos(cosphi) /3; |
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64 | pit = 3.14159265358979/3; |
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65 | |
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66 | r[0] = -_2R * cos(phit) -bt; |
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67 | r[1] = _2R * cos(pit - phit) -bt; |
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68 | r[2] = _2R * cos(pit + phit) -bt; |
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69 | } |
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70 | } |
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71 | } |
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