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openmc-dev / openmc / 21489819490

29 Jan 2026 06:21PM UTC coverage: 80.077% (-1.9%) from 81.953%
21489819490

Pull #3757

github

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Merge d08626053 into f7a734189
Pull Request #3757: Testing point detectors

16004 of 22621 branches covered (70.75%)

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94 of 518 new or added lines in 26 files covered. (18.15%)

1021 existing lines in 52 files now uncovered.

53779 of 64524 relevant lines covered (83.35%)

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95.66
/src/math_functions.cpp
1
#include "openmc/math_functions.h"
2

3
#include "openmc/external/Faddeeva.hh"
4

5
#include "openmc/constants.h"
6
#include "openmc/random_lcg.h"
7

8
namespace openmc {
9

10
//==============================================================================
11
// Mathematical methods
12
//==============================================================================
13

14
double normal_percentile(double p)
13✔
15
{
16
  constexpr double p_low = 0.02425;
13✔
17
  constexpr double a[6] = {-3.969683028665376e1, 2.209460984245205e2,
18
    -2.759285104469687e2, 1.383577518672690e2, -3.066479806614716e1,
19
    2.506628277459239e0};
20
  constexpr double b[5] = {-5.447609879822406e1, 1.615858368580409e2,
21
    -1.556989798598866e2, 6.680131188771972e1, -1.328068155288572e1};
22
  constexpr double c[6] = {-7.784894002430293e-3, -3.223964580411365e-1,
23
    -2.400758277161838, -2.549732539343734, 4.374664141464968,
24
    2.938163982698783};
25
  constexpr double d[4] = {7.784695709041462e-3, 3.224671290700398e-1,
26
    2.445134137142996, 3.754408661907416};
27

28
  // The rational approximation used here is from an unpublished work at
29
  // http://home.online.no/~pjacklam/notes/invnorm/
30

31
  double z;
32
  double q;
33

34
  if (p < p_low) {
13✔
35
    // Rational approximation for lower region.
36

37
    q = std::sqrt(-2.0 * std::log(p));
1✔
38
    z = (((((c[0] * q + c[1]) * q + c[2]) * q + c[3]) * q + c[4]) * q + c[5]) /
1✔
39
        ((((d[0] * q + d[1]) * q + d[2]) * q + d[3]) * q + 1.0);
1✔
40

41
  } else if (p <= 1.0 - p_low) {
12✔
42
    // Rational approximation for central region
43
    q = p - 0.5;
11✔
44
    double r = q * q;
11✔
45
    z = (((((a[0] * r + a[1]) * r + a[2]) * r + a[3]) * r + a[4]) * r + a[5]) *
11✔
46
        q /
47
        (((((b[0] * r + b[1]) * r + b[2]) * r + b[3]) * r + b[4]) * r + 1.0);
11✔
48

49
  } else {
50
    // Rational approximation for upper region
51

52
    q = std::sqrt(-2.0 * std::log(1.0 - p));
1✔
53
    z = -(((((c[0] * q + c[1]) * q + c[2]) * q + c[3]) * q + c[4]) * q + c[5]) /
1✔
54
        ((((d[0] * q + d[1]) * q + d[2]) * q + d[3]) * q + 1.0);
1✔
55
  }
56

57
  // Refinement based on Newton's method
58

59
  z = z - (0.5 * std::erfc(-z / std::sqrt(2.0)) - p) * std::sqrt(2.0 * PI) *
13✔
60
            std::exp(0.5 * z * z);
13✔
61

62
  return z;
13✔
63
}
64

65
double t_percentile(double p, int df)
25✔
66
{
67
  double t;
68

69
  if (df == 1) {
25✔
70
    // For one degree of freedom, the t-distribution becomes a Cauchy
71
    // distribution whose cdf we can invert directly
72

73
    t = std::tan(PI * (p - 0.5));
6✔
74
  } else if (df == 2) {
19✔
75
    // For two degrees of freedom, the cdf is given by 1/2 + x/(2*sqrt(x^2 +
76
    // 2)). This can be directly inverted to yield the solution below
77

78
    t = 2.0 * std::sqrt(2.0) * (p - 0.5) /
6✔
79
        std::sqrt(1. - 4. * std::pow(p - 0.5, 2.));
6✔
80
  } else {
81
    // This approximation is from E. Olusegun George and Meenakshi Sivaram, "A
82
    // modification of the Fisher-Cornish approximation for the student t
83
    // percentiles," Communication in Statistics - Simulation and Computation,
84
    // 16 (4), pp. 1123-1132 (1987).
85
    double n = df;
13✔
86
    double k = 1. / (n - 2.);
13✔
87
    double z = normal_percentile(p);
13✔
88
    double z2 = z * z;
13✔
89
    t = std::sqrt(n * k) *
13✔
90
        (z + (z2 - 3.) * z * k / 4. +
13✔
91
          ((5. * z2 - 56.) * z2 + 75.) * z * k * k / 96. +
13✔
92
          (((z2 - 27.) * 3. * z2 + 417.) * z2 - 315.) * z * k * k * k / 384.);
13✔
93
  }
94

95
  return t;
25✔
96
}
97

98
void calc_pn_c(int n, double x, double pnx[])
31,933,392✔
99
{
100
  pnx[0] = 1.;
31,933,392✔
101
  if (n >= 1) {
31,933,392✔
102
    pnx[1] = x;
10,340,293✔
103
  }
104

105
  // Use recursion relation to build the higher orders
106
  for (int l = 1; l < n; l++) {
32,417,499✔
107
    pnx[l + 1] = ((2 * l + 1) * x * pnx[l] - l * pnx[l - 1]) / (l + 1);
484,107✔
108
  }
109
}
31,933,392✔
110

111
double evaluate_legendre(int n, const double data[], double x)
7,428,060✔
112
{
113
  double* pnx = new double[n + 1];
7,428,060!
114
  double val = 0.0;
7,428,060✔
115
  calc_pn_c(n, x, pnx);
7,428,060✔
116
  for (int l = 0; l <= n; l++) {
19,244,617✔
117
    val += (l + 0.5) * data[l] * pnx[l];
11,816,557✔
118
  }
119
  delete[] pnx;
7,428,060!
120
  return val;
7,428,060✔
121
}
122

123
void calc_rn_c(int n, const double uvw[3], double rn[])
1✔
124
{
125
  Direction u {uvw};
1✔
126
  calc_rn(n, u, rn);
1✔
127
}
1✔
128

129
void calc_rn(int n, Direction u, double rn[])
415,304✔
130
{
131
  // rn[] is assumed to have already been allocated to the correct size
132

133
  // Store the cosine of the polar angle and the azimuthal angle
134
  double w = u.z;
415,304✔
135
  double phi;
136
  if (u.x == 0.) {
415,304!
137
    phi = 0.;
×
138
  } else {
139
    phi = std::atan2(u.y, u.x);
415,304✔
140
  }
141

142
  // Store the shorthand of 1-w * w
143
  double w2m1 = 1. - w * w;
415,304✔
144

145
  // Now evaluate the spherical harmonics function
146
  rn[0] = 1.;
415,304✔
147
  int i = 0;
415,304✔
148
  for (int l = 1; l <= n; l++) {
2,076,798✔
149
    // Set the index to the start of this order
150
    i += 2 * (l - 1) + 1;
1,661,494✔
151

152
    // Now evaluate each
153
    switch (l) {
1,661,494!
154
    case 1:
415,304✔
155
      // l = 1, m = -1
156
      rn[i] = -(std::sqrt(w2m1) * std::sin(phi));
415,304✔
157
      // l = 1, m = 0
158
      rn[i + 1] = w;
415,304✔
159
      // l = 1, m = 1
160
      rn[i + 2] = -(std::sqrt(w2m1) * std::cos(phi));
415,304✔
161
      break;
415,304✔
162
    case 2:
415,304✔
163
      // l = 2, m = -2
164
      rn[i] = 0.288675134594813 * (-3. * w * w + 3.) * std::sin(2. * phi);
415,304✔
165
      // l = 2, m = -1
166
      rn[i + 1] = -(1.73205080756888 * w * std::sqrt(w2m1) * std::sin(phi));
415,304✔
167
      // l = 2, m = 0
168
      rn[i + 2] = 1.5 * w * w - 0.5;
415,304✔
169
      // l = 2, m = 1
170
      rn[i + 3] = -(1.73205080756888 * w * std::sqrt(w2m1) * std::cos(phi));
415,304✔
171
      // l = 2, m = 2
172
      rn[i + 4] = 0.288675134594813 * (-3. * w * w + 3.) * std::cos(2. * phi);
415,304✔
173
      break;
415,304✔
174
    case 3:
415,304✔
175
      // l = 3, m = -3
176
      rn[i] = -(0.790569415042095 * std::pow(w2m1, 1.5) * std::sin(3. * phi));
415,304✔
177
      // l = 3, m = -2
178
      rn[i + 1] = 1.93649167310371 * w * (w2m1)*std::sin(2. * phi);
415,304✔
179
      // l = 3, m = -1
180
      rn[i + 2] = -(0.408248290463863 * std::sqrt(w2m1) *
415,304✔
181
                    ((7.5) * w * w - 3. / 2.) * std::sin(phi));
415,304✔
182
      // l = 3, m = 0
183
      rn[i + 3] = 2.5 * std::pow(w, 3) - 1.5 * w;
415,304✔
184
      // l = 3, m = 1
185
      rn[i + 4] = -(0.408248290463863 * std::sqrt(w2m1) *
415,304✔
186
                    ((7.5) * w * w - 3. / 2.) * std::cos(phi));
415,304✔
187
      // l = 3, m = 2
188
      rn[i + 5] = 1.93649167310371 * w * (w2m1)*std::cos(2. * phi);
415,304✔
189
      // l = 3, m = 3
190
      rn[i + 6] =
415,304✔
191
        -(0.790569415042095 * std::pow(w2m1, 1.5) * std::cos(3. * phi));
415,304✔
192
      break;
415,304✔
193
    case 4:
415,304✔
194
      // l = 4, m = -4
195
      rn[i] = 0.739509972887452 * (w2m1 * w2m1) * std::sin(4.0 * phi);
415,304✔
196
      // l = 4, m = -3
197
      rn[i + 1] =
415,304✔
198
        -(2.09165006633519 * w * std::pow(w2m1, 1.5) * std::sin(3. * phi));
415,304✔
199
      // l = 4, m = -2
200
      rn[i + 2] =
415,304✔
201
        0.074535599249993 * (w2m1) * (52.5 * w * w - 7.5) * std::sin(2. * phi);
415,304✔
202
      // l = 4, m = -1
203
      rn[i + 3] = -(0.316227766016838 * std::sqrt(w2m1) *
830,608✔
204
                    (17.5 * std::pow(w, 3) - 7.5 * w) * std::sin(phi));
415,304✔
205
      // l = 4, m = 0
206
      rn[i + 4] = 4.375 * std::pow(w, 4) - 3.75 * w * w + 0.375;
415,304✔
207
      // l = 4, m = 1
208
      rn[i + 5] = -(0.316227766016838 * std::sqrt(w2m1) *
830,608✔
209
                    (17.5 * std::pow(w, 3) - 7.5 * w) * std::cos(phi));
415,304✔
210
      // l = 4, m = 2
211
      rn[i + 6] =
415,304✔
212
        0.074535599249993 * (w2m1) * (52.5 * w * w - 7.5) * std::cos(2. * phi);
415,304✔
213
      // l = 4, m = 3
214
      rn[i + 7] =
415,304✔
215
        -(2.09165006633519 * w * std::pow(w2m1, 1.5) * std::cos(3. * phi));
415,304✔
216
      // l = 4, m = 4
217
      rn[i + 8] = 0.739509972887452 * w2m1 * w2m1 * std::cos(4.0 * phi);
415,304✔
218
      break;
415,304✔
219
    case 5:
273✔
220
      // l = 5, m = -5
221
      rn[i] = -(0.701560760020114 * std::pow(w2m1, 2.5) * std::sin(5.0 * phi));
273✔
222
      // l = 5, m = -4
223
      rn[i + 1] = 2.21852991866236 * w * w2m1 * w2m1 * std::sin(4.0 * phi);
273✔
224
      // l = 5, m = -3
225
      rn[i + 2] = -(0.00996023841111995 * std::pow(w2m1, 1.5) *
273✔
226
                    ((945.0 / 2.) * w * w - 52.5) * std::sin(3. * phi));
273✔
227
      // l = 5, m = -2
228
      rn[i + 3] = 0.0487950036474267 * (w2m1) *
546✔
229
                  ((315.0 / 2.) * std::pow(w, 3) - 52.5 * w) *
273✔
230
                  std::sin(2. * phi);
273✔
231
      // l = 5, m = -1
232
      rn[i + 4] =
273✔
233
        -(0.258198889747161 * std::sqrt(w2m1) *
546✔
234
          (39.375 * std::pow(w, 4) - 105.0 / 4.0 * w * w + 15.0 / 8.0) *
273✔
235
          std::sin(phi));
273✔
236
      // l = 5, m = 0
237
      rn[i + 5] = 7.875 * std::pow(w, 5) - 8.75 * std::pow(w, 3) + 1.875 * w;
273✔
238
      // l = 5, m = 1
239
      rn[i + 6] =
273✔
240
        -(0.258198889747161 * std::sqrt(w2m1) *
546✔
241
          (39.375 * std::pow(w, 4) - 105.0 / 4.0 * w * w + 15.0 / 8.0) *
273✔
242
          std::cos(phi));
273✔
243
      // l = 5, m = 2
244
      rn[i + 7] = 0.0487950036474267 * (w2m1) *
546✔
245
                  ((315.0 / 2.) * std::pow(w, 3) - 52.5 * w) *
273✔
246
                  std::cos(2. * phi);
273✔
247
      // l = 5, m = 3
248
      rn[i + 8] = -(0.00996023841111995 * std::pow(w2m1, 1.5) *
273✔
249
                    ((945.0 / 2.) * w * w - 52.5) * std::cos(3. * phi));
273✔
250
      // l = 5, m = 4
251
      rn[i + 9] = 2.21852991866236 * w * w2m1 * w2m1 * std::cos(4.0 * phi);
273✔
252
      // l = 5, m = 5
253
      rn[i + 10] =
273✔
254
        -(0.701560760020114 * std::pow(w2m1, 2.5) * std::cos(5.0 * phi));
273✔
255
      break;
273✔
256
    case 6:
1✔
257
      // l = 6, m = -6
258
      rn[i] = 0.671693289381396 * std::pow(w2m1, 3) * std::sin(6.0 * phi);
1✔
259
      // l = 6, m = -5
260
      rn[i + 1] =
1✔
261
        -(2.32681380862329 * w * std::pow(w2m1, 2.5) * std::sin(5.0 * phi));
1✔
262
      // l = 6, m = -4
263
      rn[i + 2] = 0.00104990131391452 * w2m1 * w2m1 *
1✔
264
                  ((10395.0 / 2.) * w * w - 945.0 / 2.) * std::sin(4.0 * phi);
1✔
265
      // l = 6, m = -3
266
      rn[i + 3] = -(0.00575054632785295 * std::pow(w2m1, 1.5) *
2✔
267
                    ((3465.0 / 2.) * std::pow(w, 3) - 945.0 / 2. * w) *
1✔
268
                    std::sin(3. * phi));
1✔
269
      // l = 6, m = -2
270
      rn[i + 4] =
1✔
271
        0.0345032779671177 * (w2m1) *
2✔
272
        ((3465.0 / 8.0) * std::pow(w, 4) - 945.0 / 4.0 * w * w + 105.0 / 8.0) *
1✔
273
        std::sin(2. * phi);
1✔
274
      // l = 6, m = -1
275
      rn[i + 5] = -(0.218217890235992 * std::sqrt(w2m1) *
2✔
276
                    ((693.0 / 8.0) * std::pow(w, 5) -
1✔
277
                      315.0 / 4.0 * std::pow(w, 3) + (105.0 / 8.0) * w) *
1✔
278
                    std::sin(phi));
1✔
279
      // l = 6, m = 0
280
      rn[i + 6] = 14.4375 * std::pow(w, 6) - 19.6875 * std::pow(w, 4) +
1✔
281
                  6.5625 * w * w - 0.3125;
1✔
282
      // l = 6, m = 1
283
      rn[i + 7] = -(0.218217890235992 * std::sqrt(w2m1) *
2✔
284
                    ((693.0 / 8.0) * std::pow(w, 5) -
1✔
285
                      315.0 / 4.0 * std::pow(w, 3) + (105.0 / 8.0) * w) *
1✔
286
                    std::cos(phi));
1✔
287
      // l = 6, m = 2
288
      rn[i + 8] =
1✔
289
        0.0345032779671177 * w2m1 *
2✔
290
        ((3465.0 / 8.0) * std::pow(w, 4) - 945.0 / 4.0 * w * w + 105.0 / 8.0) *
1✔
291
        std::cos(2. * phi);
1✔
292
      // l = 6, m = 3
293
      rn[i + 9] = -(0.00575054632785295 * std::pow(w2m1, 1.5) *
2✔
294
                    ((3465.0 / 2.) * std::pow(w, 3) - 945.0 / 2. * w) *
1✔
295
                    std::cos(3. * phi));
1✔
296
      // l = 6, m = 4
297
      rn[i + 10] = 0.00104990131391452 * w2m1 * w2m1 *
1✔
298
                   ((10395.0 / 2.) * w * w - 945.0 / 2.) * std::cos(4.0 * phi);
1✔
299
      // l = 6, m = 5
300
      rn[i + 11] =
1✔
301
        -(2.32681380862329 * w * std::pow(w2m1, 2.5) * std::cos(5.0 * phi));
1✔
302
      // l = 6, m = 6
303
      rn[i + 12] = 0.671693289381396 * std::pow(w2m1, 3) * std::cos(6.0 * phi);
1✔
304
      break;
1✔
305
    case 7:
1✔
306
      // l = 7, m = -7
307
      rn[i] = -(0.647259849287749 * std::pow(w2m1, 3.5) * std::sin(7.0 * phi));
1✔
308
      // l = 7, m = -6
309
      rn[i + 1] =
1✔
310
        2.42182459624969 * w * std::pow(w2m1, 3) * std::sin(6.0 * phi);
1✔
311
      // l = 7, m = -5
312
      rn[i + 2] =
1✔
313
        -(9.13821798555235e-5 * std::pow(w2m1, 2.5) *
1✔
314
          ((135135.0 / 2.) * w * w - 10395.0 / 2.) * std::sin(5.0 * phi));
1✔
315
      // l = 7, m = -4
316
      rn[i + 3] = 0.000548293079133141 * w2m1 * w2m1 *
2✔
317
                  ((45045.0 / 2.) * std::pow(w, 3) - 10395.0 / 2. * w) *
1✔
318
                  std::sin(4.0 * phi);
1✔
319
      // l = 7, m = -3
320
      rn[i + 4] = -(0.00363696483726654 * std::pow(w2m1, 1.5) *
2✔
321
                    ((45045.0 / 8.0) * std::pow(w, 4) - 10395.0 / 4.0 * w * w +
1✔
322
                      945.0 / 8.0) *
1✔
323
                    std::sin(3. * phi));
1✔
324
      // l = 7, m = -2
325
      rn[i + 5] = 0.025717224993682 * (w2m1) *
2✔
326
                  ((9009.0 / 8.0) * std::pow(w, 5) -
1✔
327
                    3465.0 / 4.0 * std::pow(w, 3) + (945.0 / 8.0) * w) *
1✔
328
                  std::sin(2. * phi);
1✔
329
      // l = 7, m = -1
330
      rn[i + 6] =
1✔
331
        -(0.188982236504614 * std::sqrt(w2m1) *
2✔
332
          ((3003.0 / 16.0) * std::pow(w, 6) - 3465.0 / 16.0 * std::pow(w, 4) +
1✔
333
            (945.0 / 16.0) * w * w - 35.0 / 16.0) *
1✔
334
          std::sin(phi));
1✔
335
      // l = 7, m = 0
336
      rn[i + 7] = 26.8125 * std::pow(w, 7) - 43.3125 * std::pow(w, 5) +
1✔
337
                  19.6875 * std::pow(w, 3) - 2.1875 * w;
1✔
338
      // l = 7, m = 1
339
      rn[i + 8] =
1✔
340
        -(0.188982236504614 * std::sqrt(w2m1) *
2✔
341
          ((3003.0 / 16.0) * std::pow(w, 6) - 3465.0 / 16.0 * std::pow(w, 4) +
1✔
342
            (945.0 / 16.0) * w * w - 35.0 / 16.0) *
1✔
343
          std::cos(phi));
1✔
344
      // l = 7, m = 2
345
      rn[i + 9] = 0.025717224993682 * (w2m1) *
2✔
346
                  ((9009.0 / 8.0) * std::pow(w, 5) -
1✔
347
                    3465.0 / 4.0 * std::pow(w, 3) + (945.0 / 8.0) * w) *
1✔
348
                  std::cos(2. * phi);
1✔
349
      // l = 7, m = 3
350
      rn[i + 10] = -(0.00363696483726654 * std::pow(w2m1, 1.5) *
2✔
351
                     ((45045.0 / 8.0) * std::pow(w, 4) - 10395.0 / 4.0 * w * w +
1✔
352
                       945.0 / 8.0) *
1✔
353
                     std::cos(3. * phi));
1✔
354
      // l = 7, m = 4
355
      rn[i + 11] = 0.000548293079133141 * w2m1 * w2m1 *
2✔
356
                   ((45045.0 / 2.) * std::pow(w, 3) - 10395.0 / 2. * w) *
1✔
357
                   std::cos(4.0 * phi);
1✔
358
      // l = 7, m = 5
359
      rn[i + 12] =
1✔
360
        -(9.13821798555235e-5 * std::pow(w2m1, 2.5) *
1✔
361
          ((135135.0 / 2.) * w * w - 10395.0 / 2.) * std::cos(5.0 * phi));
1✔
362
      // l = 7, m = 6
363
      rn[i + 13] =
1✔
364
        2.42182459624969 * w * std::pow(w2m1, 3) * std::cos(6.0 * phi);
1✔
365
      // l = 7, m = 7
366
      rn[i + 14] =
1✔
367
        -(0.647259849287749 * std::pow(w2m1, 3.5) * std::cos(7.0 * phi));
1✔
368
      break;
1✔
369
    case 8:
1✔
370
      // l = 8, m = -8
371
      rn[i] = 0.626706654240044 * std::pow(w2m1, 4) * std::sin(8.0 * phi);
1✔
372
      // l = 8, m = -7
373
      rn[i + 1] =
1✔
374
        -(2.50682661696018 * w * std::pow(w2m1, 3.5) * std::sin(7.0 * phi));
1✔
375
      // l = 8, m = -6
376
      rn[i + 2] = 6.77369783729086e-6 * std::pow(w2m1, 3) *
1✔
377
                  ((2027025.0 / 2.) * w * w - 135135.0 / 2.) *
1✔
378
                  std::sin(6.0 * phi);
1✔
379
      // l = 8, m = -5
380
      rn[i + 3] = -(4.38985792528482e-5 * std::pow(w2m1, 2.5) *
2✔
381
                    ((675675.0 / 2.) * std::pow(w, 3) - 135135.0 / 2. * w) *
1✔
382
                    std::sin(5.0 * phi));
1✔
383
      // l = 8, m = -4
384
      rn[i + 4] = 0.000316557156832328 * w2m1 * w2m1 *
2✔
385
                  ((675675.0 / 8.0) * std::pow(w, 4) - 135135.0 / 4.0 * w * w +
1✔
386
                    10395.0 / 8.0) *
1✔
387
                  std::sin(4.0 * phi);
1✔
388
      // l = 8, m = -3
389
      rn[i + 5] = -(0.00245204119306875 * std::pow(w2m1, 1.5) *
2✔
390
                    ((135135.0 / 8.0) * std::pow(w, 5) -
1✔
391
                      45045.0 / 4.0 * std::pow(w, 3) + (10395.0 / 8.0) * w) *
1✔
392
                    std::sin(3. * phi));
1✔
393
      // l = 8, m = -2
394
      rn[i + 6] =
1✔
395
        0.0199204768222399 * (w2m1) *
2✔
396
        ((45045.0 / 16.0) * std::pow(w, 6) - 45045.0 / 16.0 * std::pow(w, 4) +
1✔
397
          (10395.0 / 16.0) * w * w - 315.0 / 16.0) *
1✔
398
        std::sin(2. * phi);
1✔
399
      // l = 8, m = -1
400
      rn[i + 7] =
1✔
401
        -(0.166666666666667 * std::sqrt(w2m1) *
2✔
402
          ((6435.0 / 16.0) * std::pow(w, 7) - 9009.0 / 16.0 * std::pow(w, 5) +
1✔
403
            (3465.0 / 16.0) * std::pow(w, 3) - 315.0 / 16.0 * w) *
1✔
404
          std::sin(phi));
1✔
405
      // l = 8, m = 0
406
      rn[i + 8] = 50.2734375 * std::pow(w, 8) - 93.84375 * std::pow(w, 6) +
1✔
407
                  54.140625 * std::pow(w, 4) - 9.84375 * w * w + 0.2734375;
1✔
408
      // l = 8, m = 1
409
      rn[i + 9] =
1✔
410
        -(0.166666666666667 * std::sqrt(w2m1) *
2✔
411
          ((6435.0 / 16.0) * std::pow(w, 7) - 9009.0 / 16.0 * std::pow(w, 5) +
1✔
412
            (3465.0 / 16.0) * std::pow(w, 3) - 315.0 / 16.0 * w) *
1✔
413
          std::cos(phi));
1✔
414
      // l = 8, m = 2
415
      rn[i + 10] =
1✔
416
        0.0199204768222399 * (w2m1) *
2✔
417
        ((45045.0 / 16.0) * std::pow(w, 6) - 45045.0 / 16.0 * std::pow(w, 4) +
1✔
418
          (10395.0 / 16.0) * w * w - 315.0 / 16.0) *
1✔
419
        std::cos(2. * phi);
1✔
420
      // l = 8, m = 3
421
      rn[i + 11] = -(0.00245204119306875 * std::pow(w2m1, 1.5) *
2✔
422
                     ((135135.0 / 8.0) * std::pow(w, 5) -
1✔
423
                       45045.0 / 4.0 * std::pow(w, 3) + (10395.0 / 8.0) * w) *
1✔
424
                     std::cos(3. * phi));
1✔
425
      // l = 8, m = 4
426
      rn[i + 12] = 0.000316557156832328 * w2m1 * w2m1 *
2✔
427
                   ((675675.0 / 8.0) * std::pow(w, 4) - 135135.0 / 4.0 * w * w +
1✔
428
                     10395.0 / 8.0) *
1✔
429
                   std::cos(4.0 * phi);
1✔
430
      // l = 8, m = 5
431
      rn[i + 13] = -(4.38985792528482e-5 * std::pow(w2m1, 2.5) *
2✔
432
                     ((675675.0 / 2.) * std::pow(w, 3) - 135135.0 / 2. * w) *
1✔
433
                     std::cos(5.0 * phi));
1✔
434
      // l = 8, m = 6
435
      rn[i + 14] = 6.77369783729086e-6 * std::pow(w2m1, 3) *
1✔
436
                   ((2027025.0 / 2.) * w * w - 135135.0 / 2.) *
1✔
437
                   std::cos(6.0 * phi);
1✔
438
      // l = 8, m = 7
439
      rn[i + 15] =
1✔
440
        -(2.50682661696018 * w * std::pow(w2m1, 3.5) * std::cos(7.0 * phi));
1✔
441
      // l = 8, m = 8
442
      rn[i + 16] = 0.626706654240044 * std::pow(w2m1, 4) * std::cos(8.0 * phi);
1✔
443
      break;
1✔
444
    case 9:
1✔
445
      // l = 9, m = -9
446
      rn[i] = -(0.609049392175524 * std::pow(w2m1, 4.5) * std::sin(9.0 * phi));
1✔
447
      // l = 9, m = -8
448
      rn[i + 1] =
1✔
449
        2.58397773170915 * w * std::pow(w2m1, 4) * std::sin(8.0 * phi);
1✔
450
      // l = 9, m = -7
451
      rn[i + 2] =
1✔
452
        -(4.37240315267812e-7 * std::pow(w2m1, 3.5) *
1✔
453
          ((34459425.0 / 2.) * w * w - 2027025.0 / 2.) * std::sin(7.0 * phi));
1✔
454
      // l = 9, m = -6
455
      rn[i + 3] = 3.02928976464514e-6 * std::pow(w2m1, 3) *
1✔
456
                  ((11486475.0 / 2.) * std::pow(w, 3) - 2027025.0 / 2. * w) *
1✔
457
                  std::sin(6.0 * phi);
1✔
458
      // l = 9, m = -5
459
      rn[i + 4] = -(2.34647776186144e-5 * std::pow(w2m1, 2.5) *
2✔
460
                    ((11486475.0 / 8.0) * std::pow(w, 4) -
1✔
461
                      2027025.0 / 4.0 * w * w + 135135.0 / 8.0) *
1✔
462
                    std::sin(5.0 * phi));
1✔
463
      // l = 9, m = -4
464
      rn[i + 5] = 0.000196320414650061 * w2m1 * w2m1 *
2✔
465
                  ((2297295.0 / 8.0) * std::pow(w, 5) -
1✔
466
                    675675.0 / 4.0 * std::pow(w, 3) + (135135.0 / 8.0) * w) *
1✔
467
                  std::sin(4.0 * phi);
1✔
468
      // l = 9, m = -3
469
      rn[i + 6] = -(
1✔
470
        0.00173385495536766 * std::pow(w2m1, 1.5) *
2✔
471
        ((765765.0 / 16.0) * std::pow(w, 6) - 675675.0 / 16.0 * std::pow(w, 4) +
1✔
472
          (135135.0 / 16.0) * w * w - 3465.0 / 16.0) *
1✔
473
        std::sin(3. * phi));
1✔
474
      // l = 9, m = -2
475
      rn[i + 7] =
1✔
476
        0.0158910431540932 * (w2m1) *
2✔
477
        ((109395.0 / 16.0) * std::pow(w, 7) - 135135.0 / 16.0 * std::pow(w, 5) +
1✔
478
          (45045.0 / 16.0) * std::pow(w, 3) - 3465.0 / 16.0 * w) *
1✔
479
        std::sin(2. * phi);
1✔
480
      // l = 9, m = -1
481
      rn[i + 8] = -(
1✔
482
        0.149071198499986 * std::sqrt(w2m1) *
2✔
483
        ((109395.0 / 128.0) * std::pow(w, 8) - 45045.0 / 32.0 * std::pow(w, 6) +
1✔
484
          (45045.0 / 64.0) * std::pow(w, 4) - 3465.0 / 32.0 * w * w +
1✔
485
          315.0 / 128.0) *
1✔
486
        std::sin(phi));
1✔
487
      // l = 9, m = 0
488
      rn[i + 9] = 94.9609375 * std::pow(w, 9) - 201.09375 * std::pow(w, 7) +
1✔
489
                  140.765625 * std::pow(w, 5) - 36.09375 * std::pow(w, 3) +
1✔
490
                  2.4609375 * w;
1✔
491
      // l = 9, m = 1
492
      rn[i + 10] = -(
1✔
493
        0.149071198499986 * std::sqrt(w2m1) *
2✔
494
        ((109395.0 / 128.0) * std::pow(w, 8) - 45045.0 / 32.0 * std::pow(w, 6) +
1✔
495
          (45045.0 / 64.0) * std::pow(w, 4) - 3465.0 / 32.0 * w * w +
1✔
496
          315.0 / 128.0) *
1✔
497
        std::cos(phi));
1✔
498
      // l = 9, m = 2
499
      rn[i + 11] =
1✔
500
        0.0158910431540932 * (w2m1) *
2✔
501
        ((109395.0 / 16.0) * std::pow(w, 7) - 135135.0 / 16.0 * std::pow(w, 5) +
1✔
502
          (45045.0 / 16.0) * std::pow(w, 3) - 3465.0 / 16.0 * w) *
1✔
503
        std::cos(2. * phi);
1✔
504
      // l = 9, m = 3
505
      rn[i + 12] = -(
1✔
506
        0.00173385495536766 * std::pow(w2m1, 1.5) *
2✔
507
        ((765765.0 / 16.0) * std::pow(w, 6) - 675675.0 / 16.0 * std::pow(w, 4) +
1✔
508
          (135135.0 / 16.0) * w * w - 3465.0 / 16.0) *
1✔
509
        std::cos(3. * phi));
1✔
510
      // l = 9, m = 4
511
      rn[i + 13] = 0.000196320414650061 * w2m1 * w2m1 *
2✔
512
                   ((2297295.0 / 8.0) * std::pow(w, 5) -
1✔
513
                     675675.0 / 4.0 * std::pow(w, 3) + (135135.0 / 8.0) * w) *
1✔
514
                   std::cos(4.0 * phi);
1✔
515
      // l = 9, m = 5
516
      rn[i + 14] = -(2.34647776186144e-5 * std::pow(w2m1, 2.5) *
2✔
517
                     ((11486475.0 / 8.0) * std::pow(w, 4) -
1✔
518
                       2027025.0 / 4.0 * w * w + 135135.0 / 8.0) *
1✔
519
                     std::cos(5.0 * phi));
1✔
520
      // l = 9, m = 6
521
      rn[i + 15] = 3.02928976464514e-6 * std::pow(w2m1, 3) *
1✔
522
                   ((11486475.0 / 2.) * std::pow(w, 3) - 2027025.0 / 2. * w) *
1✔
523
                   std::cos(6.0 * phi);
1✔
524
      // l = 9, m = 7
525
      rn[i + 16] =
1✔
526
        -(4.37240315267812e-7 * std::pow(w2m1, 3.5) *
1✔
527
          ((34459425.0 / 2.) * w * w - 2027025.0 / 2.) * std::cos(7.0 * phi));
1✔
528
      // l = 9, m = 8
529
      rn[i + 17] =
1✔
530
        2.58397773170915 * w * std::pow(w2m1, 4) * std::cos(8.0 * phi);
1✔
531
      // l = 9, m = 9
532
      rn[i + 18] =
1✔
533
        -(0.609049392175524 * std::pow(w2m1, 4.5) * std::cos(9.0 * phi));
1✔
534
      break;
1✔
535
    case 10:
1✔
536
      // l = 10, m = -10
537
      rn[i] = 0.593627917136573 * std::pow(w2m1, 5) * std::sin(10.0 * phi);
1✔
538
      // l = 10, m = -9
539
      rn[i + 1] =
1✔
540
        -(2.65478475211798 * w * std::pow(w2m1, 4.5) * std::sin(9.0 * phi));
1✔
541
      // l = 10, m = -8
542
      rn[i + 2] = 2.49953651452314e-8 * std::pow(w2m1, 4) *
1✔
543
                  ((654729075.0 / 2.) * w * w - 34459425.0 / 2.) *
1✔
544
                  std::sin(8.0 * phi);
1✔
545
      // l = 10, m = -7
546
      rn[i + 3] =
1✔
547
        -(1.83677671621093e-7 * std::pow(w2m1, 3.5) *
2✔
548
          ((218243025.0 / 2.) * std::pow(w, 3) - 34459425.0 / 2. * w) *
1✔
549
          std::sin(7.0 * phi));
1✔
550
      // l = 10, m = -6
551
      rn[i + 4] = 1.51464488232257e-6 * std::pow(w2m1, 3) *
1✔
552
                  ((218243025.0 / 8.0) * std::pow(w, 4) -
1✔
553
                    34459425.0 / 4.0 * w * w + 2027025.0 / 8.0) *
1✔
554
                  std::sin(6.0 * phi);
1✔
555
      // l = 10, m = -5
556
      rn[i + 5] =
1✔
557
        -(1.35473956745817e-5 * std::pow(w2m1, 2.5) *
2✔
558
          ((43648605.0 / 8.0) * std::pow(w, 5) -
1✔
559
            11486475.0 / 4.0 * std::pow(w, 3) + (2027025.0 / 8.0) * w) *
1✔
560
          std::sin(5.0 * phi));
1✔
561
      // l = 10, m = -4
562
      rn[i + 6] = 0.000128521880085575 * w2m1 * w2m1 *
2✔
563
                  ((14549535.0 / 16.0) * std::pow(w, 6) -
1✔
564
                    11486475.0 / 16.0 * std::pow(w, 4) +
1✔
565
                    (2027025.0 / 16.0) * w * w - 45045.0 / 16.0) *
1✔
566
                  std::sin(4.0 * phi);
1✔
567
      // l = 10, m = -3
568
      rn[i + 7] = -(0.00127230170115096 * std::pow(w2m1, 1.5) *
2✔
569
                    ((2078505.0 / 16.0) * std::pow(w, 7) -
1✔
570
                      2297295.0 / 16.0 * std::pow(w, 5) +
1✔
571
                      (675675.0 / 16.0) * std::pow(w, 3) - 45045.0 / 16.0 * w) *
1✔
572
                    std::sin(3. * phi));
1✔
573
      // l = 10, m = -2
574
      rn[i + 8] = 0.012974982402692 * (w2m1) *
2✔
575
                  ((2078505.0 / 128.0) * std::pow(w, 8) -
1✔
576
                    765765.0 / 32.0 * std::pow(w, 6) +
1✔
577
                    (675675.0 / 64.0) * std::pow(w, 4) -
1✔
578
                    45045.0 / 32.0 * w * w + 3465.0 / 128.0) *
1✔
579
                  std::sin(2. * phi);
1✔
580
      // l = 10, m = -1
581
      rn[i + 9] = -(0.134839972492648 * std::sqrt(w2m1) *
2✔
582
                    ((230945.0 / 128.0) * std::pow(w, 9) -
1✔
583
                      109395.0 / 32.0 * std::pow(w, 7) +
1✔
584
                      (135135.0 / 64.0) * std::pow(w, 5) -
1✔
585
                      15015.0 / 32.0 * std::pow(w, 3) + (3465.0 / 128.0) * w) *
1✔
586
                    std::sin(phi));
1✔
587
      // l = 10, m = 0
588
      rn[i + 10] = 180.42578125 * std::pow(w, 10) -
1✔
589
                   427.32421875 * std::pow(w, 8) +
1✔
590
                   351.9140625 * std::pow(w, 6) - 117.3046875 * std::pow(w, 4) +
1✔
591
                   13.53515625 * w * w - 0.24609375;
1✔
592
      // l = 10, m = 1
593
      rn[i + 11] = -(0.134839972492648 * std::sqrt(w2m1) *
2✔
594
                     ((230945.0 / 128.0) * std::pow(w, 9) -
1✔
595
                       109395.0 / 32.0 * std::pow(w, 7) +
1✔
596
                       (135135.0 / 64.0) * std::pow(w, 5) -
1✔
597
                       15015.0 / 32.0 * std::pow(w, 3) + (3465.0 / 128.0) * w) *
1✔
598
                     std::cos(phi));
1✔
599
      // l = 10, m = 2
600
      rn[i + 12] = 0.012974982402692 * (w2m1) *
2✔
601
                   ((2078505.0 / 128.0) * std::pow(w, 8) -
1✔
602
                     765765.0 / 32.0 * std::pow(w, 6) +
1✔
603
                     (675675.0 / 64.0) * std::pow(w, 4) -
1✔
604
                     45045.0 / 32.0 * w * w + 3465.0 / 128.0) *
1✔
605
                   std::cos(2. * phi);
1✔
606
      // l = 10, m = 3
607
      rn[i + 13] =
1✔
608
        -(0.00127230170115096 * std::pow(w2m1, 1.5) *
2✔
609
          ((2078505.0 / 16.0) * std::pow(w, 7) -
1✔
610
            2297295.0 / 16.0 * std::pow(w, 5) +
1✔
611
            (675675.0 / 16.0) * std::pow(w, 3) - 45045.0 / 16.0 * w) *
1✔
612
          std::cos(3. * phi));
1✔
613
      // l = 10, m = 4
614
      rn[i + 14] = 0.000128521880085575 * w2m1 * w2m1 *
2✔
615
                   ((14549535.0 / 16.0) * std::pow(w, 6) -
1✔
616
                     11486475.0 / 16.0 * std::pow(w, 4) +
1✔
617
                     (2027025.0 / 16.0) * w * w - 45045.0 / 16.0) *
1✔
618
                   std::cos(4.0 * phi);
1✔
619
      // l = 10, m = 5
620
      rn[i + 15] =
1✔
621
        -(1.35473956745817e-5 * std::pow(w2m1, 2.5) *
2✔
622
          ((43648605.0 / 8.0) * std::pow(w, 5) -
1✔
623
            11486475.0 / 4.0 * std::pow(w, 3) + (2027025.0 / 8.0) * w) *
1✔
624
          std::cos(5.0 * phi));
1✔
625
      // l = 10, m = 6
626
      rn[i + 16] = 1.51464488232257e-6 * std::pow(w2m1, 3) *
1✔
627
                   ((218243025.0 / 8.0) * std::pow(w, 4) -
1✔
628
                     34459425.0 / 4.0 * w * w + 2027025.0 / 8.0) *
1✔
629
                   std::cos(6.0 * phi);
1✔
630
      // l = 10, m = 7
631
      rn[i + 17] =
1✔
632
        -(1.83677671621093e-7 * std::pow(w2m1, 3.5) *
2✔
633
          ((218243025.0 / 2.) * std::pow(w, 3) - 34459425.0 / 2. * w) *
1✔
634
          std::cos(7.0 * phi));
1✔
635
      // l = 10, m = 8
636
      rn[i + 18] = 2.49953651452314e-8 * std::pow(w2m1, 4) *
1✔
637
                   ((654729075.0 / 2.) * w * w - 34459425.0 / 2.) *
1✔
638
                   std::cos(8.0 * phi);
1✔
639
      // l = 10, m = 9
640
      rn[i + 19] =
1✔
641
        -(2.65478475211798 * w * std::pow(w2m1, 4.5) * std::cos(9.0 * phi));
1✔
642
      // l = 10, m = 10
643
      rn[i + 20] = 0.593627917136573 * std::pow(w2m1, 5) * std::cos(10.0 * phi);
1✔
644
    }
645
  }
646
}
415,304✔
647

648
void calc_zn(int n, double rho, double phi, double zn[])
245,870✔
649
{
650
  // ===========================================================================
651
  // Determine vector of sin(n*phi) and cos(n*phi). This takes advantage of the
652
  // following recurrence relations so that only a single sin/cos have to be
653
  // evaluated (https://mathworld.wolfram.com/Multiple-AngleFormulas.html)
654
  //
655
  // sin(nx) = 2 cos(x) sin((n-1)x) - sin((n-2)x)
656
  // cos(nx) = 2 cos(x) cos((n-1)x) - cos((n-2)x)
657

658
  double sin_phi = std::sin(phi);
245,870✔
659
  double cos_phi = std::cos(phi);
245,870✔
660

661
  vector<double> sin_phi_vec(n + 1); // Sin[n * phi]
245,870✔
662
  vector<double> cos_phi_vec(n + 1); // Cos[n * phi]
245,870✔
663
  sin_phi_vec[0] = 1.0;
245,870✔
664
  cos_phi_vec[0] = 1.0;
245,870✔
665
  sin_phi_vec[1] = 2.0 * cos_phi;
245,870✔
666
  cos_phi_vec[1] = cos_phi;
245,870✔
667

668
  for (int i = 2; i <= n; i++) {
1,229,065✔
669
    sin_phi_vec[i] = 2. * cos_phi * sin_phi_vec[i - 1] - sin_phi_vec[i - 2];
983,195✔
670
    cos_phi_vec[i] = 2. * cos_phi * cos_phi_vec[i - 1] - cos_phi_vec[i - 2];
983,195✔
671
  }
672

673
  for (int i = 0; i <= n; i++) {
1,720,805✔
674
    sin_phi_vec[i] *= sin_phi;
1,474,935✔
675
  }
676

677
  // ===========================================================================
678
  // Calculate R_pq(rho)
679
  // Matrix forms of the coefficients which are easier to work with
680
  vector<vector<double>> zn_mat(n + 1, vector<double>(n + 1));
491,740✔
681

682
  // Fill the main diagonal first (Eq 3.9 in Chong)
683
  for (int p = 0; p <= n; p++) {
1,720,805✔
684
    zn_mat[p][p] = std::pow(rho, p);
1,474,935✔
685
  }
686

687
  // Fill the 2nd diagonal (Eq 3.10 in Chong)
688
  for (int q = 0; q <= n - 2; q++) {
1,229,065✔
689
    zn_mat[q][q + 2] = (q + 2) * zn_mat[q + 2][q + 2] - (q + 1) * zn_mat[q][q];
983,195✔
690
  }
691

692
  // Fill in the rest of the values using the original results (Eq. 3.8 in
693
  // Chong)
694
  for (int p = 4; p <= n; p++) {
737,325✔
695
    double k2 = 2 * p * (p - 1) * (p - 2);
491,455✔
696
    for (int q = p - 4; q >= 0; q -= 2) {
982,919✔
697
      double k1 = ((p + q) * (p - q) * (p - 2)) / 2.;
491,464✔
698
      double k3 = -q * q * (p - 1) - p * (p - 1) * (p - 2);
491,464✔
699
      double k4 = (-p * (p + q - 2) * (p - q - 2)) / 2.;
491,464✔
700
      zn_mat[q][p] =
491,464✔
701
        ((k2 * rho * rho + k3) * zn_mat[q][p - 2] + k4 * zn_mat[q][p - 4]) / k1;
491,464✔
702
    }
703
  }
704

705
  // Roll into a single vector for easier computation later
706
  // The vector is ordered (0,0), (1,-1), (1,1), (2,-2), (2,0),
707
  // (2, 2), ....   in (n,m) indices
708
  // Note that the cos and sin vectors are offset by one
709
  // sin_phi_vec = [sin(x), sin(2x), sin(3x) ...]
710
  // cos_phi_vec = [1.0, cos(x), cos(2x)... ]
711
  int i = 0;
245,870✔
712
  for (int p = 0; p <= n; p++) {
1,720,805✔
713
    for (int q = -p; q <= p; q += 2) {
6,636,646✔
714
      if (q < 0) {
5,161,711✔
715
        zn[i] = zn_mat[std::abs(q)][p] * sin_phi_vec[std::abs(q) - 1];
2,212,117✔
716
      } else if (q == 0) {
2,949,594✔
717
        zn[i] = zn_mat[q][p];
737,477✔
718
      } else {
719
        zn[i] = zn_mat[q][p] * cos_phi_vec[q];
2,212,117✔
720
      }
721
      i++;
5,161,711✔
722
    }
723
  }
724
}
245,870✔
725

726
void calc_zn_rad(int n, double rho, double zn_rad[])
4✔
727
{
728
  // Calculate R_p0(rho) as Zn_p0(rho)
729
  // Set up the array of the coefficients
730

731
  double q = 0;
4✔
732

733
  // R_00 is always 1
734
  zn_rad[0] = 1;
4✔
735

736
  // Fill in the rest of the array (Eq 3.8 and Eq 3.10 in Chong)
737
  for (int p = 2; p <= n; p += 2) {
24✔
738
    int index = int(p / 2);
20✔
739
    if (p == 2) {
20✔
740
      // Setting up R_22 to calculate R_20 (Eq 3.10 in Chong)
741
      double R_22 = rho * rho;
4✔
742
      zn_rad[index] = 2 * R_22 - zn_rad[0];
4✔
743
    } else {
744
      double k1 = ((p + q) * (p - q) * (p - 2)) / 2.;
16✔
745
      double k2 = 2 * p * (p - 1) * (p - 2);
16✔
746
      double k3 = -q * q * (p - 1) - p * (p - 1) * (p - 2);
16✔
747
      double k4 = (-p * (p + q - 2) * (p - q - 2)) / 2.;
16✔
748
      zn_rad[index] =
16✔
749
        ((k2 * rho * rho + k3) * zn_rad[index - 1] + k4 * zn_rad[index - 2]) /
16✔
750
        k1;
751
    }
752
  }
753
}
4✔
754

755
void rotate_angle_c(double uvw[3], double mu, const double* phi, uint64_t* seed)
3✔
756
{
757
  Direction u = rotate_angle({uvw}, mu, phi, seed);
3✔
758
  uvw[0] = u.x;
3✔
759
  uvw[1] = u.y;
3✔
760
  uvw[2] = u.z;
3✔
761
}
3✔
762

763
Direction rotate_angle(
266,802,559✔
764
  Direction u, double mu, const double* phi, uint64_t* seed)
765
{
766
  // Sample azimuthal angle in [0,2pi) if none provided
767
  double phi_;
768
  if (phi != nullptr) {
266,802,559✔
769
    phi_ = (*phi);
2,014,930✔
770
  } else {
771
    phi_ = 2.0 * PI * prn(seed);
264,787,629✔
772
  }
773

774
  // Precompute factors to save flops
775
  double sinphi = std::sin(phi_);
266,802,559✔
776
  double cosphi = std::cos(phi_);
266,802,559✔
777
  double a = std::sqrt(std::fmax(0., 1. - mu * mu));
266,802,559✔
778
  double b = std::sqrt(std::fmax(0., 1. - u.z * u.z));
266,802,559✔
779

780
  // Need to treat special case where sqrt(1 - w**2) is close to zero by
781
  // expanding about the v component rather than the w component
782
  if (b > 1e-10) {
266,802,559✔
783
    return {mu * u.x + a * (u.x * u.z * cosphi - u.y * sinphi) / b,
266,767,024✔
784
      mu * u.y + a * (u.y * u.z * cosphi + u.x * sinphi) / b,
266,767,024✔
785
      mu * u.z - a * b * cosphi};
266,767,024✔
786
  } else {
787
    b = std::sqrt(1. - u.y * u.y);
35,535✔
788
    return {mu * u.x + a * (-u.x * u.y * sinphi + u.z * cosphi) / b,
35,535✔
789
      mu * u.y + a * b * sinphi,
35,535✔
790
      mu * u.z - a * (u.y * u.z * sinphi + u.x * cosphi) / b};
35,535✔
791
  }
792
}
793

794
void spline(int n, const double x[], const double y[], double z[])
7,888✔
795
{
796
  vector<double> c_new(n - 1);
7,888✔
797

798
  // Set natural boundary conditions
799
  c_new[0] = 0.0;
7,888✔
800
  z[0] = 0.0;
7,888✔
801
  z[n - 1] = 0.0;
7,888✔
802

803
  // Solve using tridiagonal matrix algorithm; first do forward sweep
804
  for (int i = 1; i < n - 1; i++) {
789,832✔
805
    double a = x[i] - x[i - 1];
781,944✔
806
    double c = x[i + 1] - x[i];
781,944✔
807
    double b = 2.0 * (a + c);
781,944✔
808
    double d = 6.0 * ((y[i + 1] - y[i]) / c - (y[i] - y[i - 1]) / a);
781,944✔
809

810
    c_new[i] = c / (b - a * c_new[i - 1]);
781,944✔
811
    z[i] = (d - a * z[i - 1]) / (b - a * c_new[i - 1]);
781,944✔
812
  }
813

814
  // Back substitution
815
  for (int i = n - 2; i >= 0; i--) {
797,720✔
816
    z[i] = z[i] - c_new[i] * z[i + 1];
789,832✔
817
  }
818
}
7,888✔
819

820
double spline_interpolate(
×
821
  int n, const double x[], const double y[], const double z[], double xint)
822
{
823
  // Find the lower bounding index in x of xint
824
  int i = n - 1;
×
825
  while (--i) {
×
826
    if (xint >= x[i])
×
827
      break;
×
828
  }
829

830
  double h = x[i + 1] - x[i];
×
831
  double r = xint - x[i];
×
832

833
  // Compute the coefficients
834
  double b = (y[i + 1] - y[i]) / h - (h / 6.0) * (z[i + 1] + 2.0 * z[i]);
×
835
  double c = z[i] / 2.0;
×
836
  double d = (z[i + 1] - z[i]) / (h * 6.0);
×
837

838
  return y[i] + b * r + c * r * r + d * r * r * r;
×
839
}
840

841
double spline_integrate(int n, const double x[], const double y[],
789,832✔
842
  const double z[], double xa, double xb)
843
{
844
  // Find the lower bounding index in x of the lower limit of integration.
845
  int ia = n - 1;
789,832✔
846
  while (--ia) {
52,741,800✔
847
    if (xa >= x[ia])
52,733,912✔
848
      break;
781,944✔
849
  }
850

851
  // Find the lower bounding index in x of the upper limit of integration.
852
  int ib = n - 1;
789,832✔
853
  while (--ib) {
51,959,856!
854
    if (xb >= x[ib])
51,959,856✔
855
      break;
789,832✔
856
  }
857

858
  // Evaluate the integral
859
  double s = 0.0;
789,832✔
860
  for (int i = ia; i <= ib; i++) {
2,361,608✔
861
    double h = x[i + 1] - x[i];
1,571,776✔
862

863
    // Compute the coefficients
864
    double b = (y[i + 1] - y[i]) / h - (h / 6.0) * (z[i + 1] + 2.0 * z[i]);
1,571,776✔
865
    double c = z[i] / 2.0;
1,571,776✔
866
    double d = (z[i + 1] - z[i]) / (h * 6.0);
1,571,776✔
867

868
    // Subtract the integral from x[ia] to xa
869
    if (i == ia) {
1,571,776✔
870
      double r = xa - x[ia];
789,832✔
871
      s = s - (y[i] * r + b / 2.0 * r * r + c / 3.0 * r * r * r +
789,832✔
872
                d / 4.0 * r * r * r * r);
789,832✔
873
    }
874

875
    // Integrate from x[ib] to xb in final interval
876
    if (i == ib) {
1,571,776✔
877
      h = xb - x[ib];
789,832✔
878
    }
879

880
    // Accumulate the integral
881
    s = s + y[i] * h + b / 2.0 * h * h + c / 3.0 * h * h * h +
1,571,776✔
882
        d / 4.0 * h * h * h * h;
1,571,776✔
883
  }
884

885
  return s;
789,832✔
886
}
887

888
std::complex<double> faddeeva(std::complex<double> z)
318,707✔
889
{
890
  // Technically, the value we want is given by the equation:
891
  // w(z) = I/pi * Integrate[Exp[-t^2]/(z-t), {t, -Infinity, Infinity}]
892
  // as shown in Equation 63 from Hwang, R. N. "A rigorous pole
893
  // representation of multilevel cross sections and its practical
894
  // applications." Nucl. Sci. Eng. 96.3 (1987): 192-209.
895
  //
896
  // The MIT Faddeeva function evaluates w(z) = exp(-z^2)erfc(-iz). These
897
  // two forms of the Faddeeva function are related by a transformation.
898
  //
899
  // If we call the integral form w_int, and the function form w_fun:
900
  // For imag(z) > 0, w_int(z) = w_fun(z)
901
  // For imag(z) < 0, w_int(z) = -conjg(w_fun(conjg(z)))
902

903
  // Note that Faddeeva::w will interpret zero as machine epsilon
904
  return z.imag() > 0.0 ? Faddeeva::w(z)
318,707!
905
                        : -std::conj(Faddeeva::w(std::conj(z)));
637,414!
906
}
907

908
std::complex<double> w_derivative(std::complex<double> z, int order)
384,777✔
909
{
910
  using namespace std::complex_literals;
911
  switch (order) {
384,777✔
912
  case 0:
128,259✔
913
    return faddeeva(z);
128,259✔
914
  case 1:
128,259✔
915
    return -2.0 * z * faddeeva(z) + 2.0i / SQRT_PI;
256,518✔
916
  default:
128,259✔
917
    return -2.0 * z * w_derivative(z, order - 1) -
128,259✔
918
           2.0 * (order - 1) * w_derivative(z, order - 2);
384,777✔
919
  }
920
}
921

NEW
922
double exprel(double x)
×
923
{
NEW
924
  if (std::abs(x) < 1e-16)
×
NEW
925
    return 1.0;
×
926
  else {
NEW
927
    return std::expm1(x) / x;
×
928
  }
929
}
930

931
// Helper function to get index and interpolation function on an incident energy
932
// grid
933
void get_energy_index(
86,723,616✔
934
  const vector<double>& energies, double E, int& i, double& f)
935
{
936
  // Get index and interpolation factor for linear-linear energy grid
937
  i = 0;
86,723,616✔
938
  f = 0.0;
86,723,616✔
939
  if (E >= energies.front()) {
86,723,616✔
940
    i = lower_bound_index(energies.begin(), energies.end(), E);
86,723,583✔
941
    if (i + 1 < energies.size())
86,723,583✔
942
      f = (E - energies[i]) / (energies[i + 1] - energies[i]);
86,723,461✔
943
  }
944
}
86,723,616✔
945

946
} // namespace openmc
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