[37] | 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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