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openmc-dev / openmc / 34176864186

08 Sep 2026 01:30AM UTC coverage: 81.371% (+0.01%) from 81.36%
34176864186

Pull #4113

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Merge 239d78ca0 into d7d3284a1
Pull Request #4113: Extract the combined k-effective estimator and fix its two-estimate branch

18707 of 27185 branches covered (68.81%)

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59 of 59 new or added lines in 2 files covered. (100.0%)

17 existing lines in 3 files now uncovered.

60597 of 70275 relevant lines covered (86.23%)

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95.73
/src/math_functions.cpp
1
#include "openmc/math_functions.h"
2

3
#include <cmath>  // for abs, sqrt
4
#include <limits> // for numeric_limits
5

6
#include "openmc/external/Faddeeva.hh"
7

8
#include "openmc/array.h"
9
#include "openmc/constants.h"
10
#include "openmc/random_lcg.h"
11

12
namespace openmc {
13

14
//==============================================================================
15
// Mathematical methods
16
//==============================================================================
17

18
double normal_percentile(double p)
163 ✔
19
{
20
  constexpr double p_low = 0.02425;
163 ✔
21
  constexpr double a[6] = {-3.969683028665376e1, 2.209460984245205e2,
163 ✔
22
    -2.759285104469687e2, 1.383577518672690e2, -3.066479806614716e1,
23
    2.506628277459239e0};
24
  constexpr double b[5] = {-5.447609879822406e1, 1.615858368580409e2,
163 ✔
25
    -1.556989798598866e2, 6.680131188771972e1, -1.328068155288572e1};
26
  constexpr double c[6] = {-7.784894002430293e-3, -3.223964580411365e-1,
163 ✔
27
    -2.400758277161838, -2.549732539343734, 4.374664141464968,
28
    2.938163982698783};
29
  constexpr double d[4] = {7.784695709041462e-3, 3.224671290700398e-1,
163 ✔
30
    2.445134137142996, 3.754408661907416};
31

32
  // The rational approximation used here is from an unpublished work at
33
  // http://home.online.no/~pjacklam/notes/invnorm/
34

35
  double z;
163 ✔
36
  double q;
163 ✔
37

38
  if (p < p_low) {
163 ✔
39
    // Rational approximation for lower region.
40

41
    q = std::sqrt(-2.0 * std::log(p));
11 ✔
42
    z = (((((c[0] * q + c[1]) * q + c[2]) * q + c[3]) * q + c[4]) * q + c[5]) /
11 ✔
43
        ((((d[0] * q + d[1]) * q + d[2]) * q + d[3]) * q + 1.0);
11 ✔
44

45
  } else if (p <= 1.0 - p_low) {
152 ✔
46
    // Rational approximation for central region
47
    q = p - 0.5;
141 ✔
48
    double r = q * q;
141 ✔
49
    z = (((((a[0] * r + a[1]) * r + a[2]) * r + a[3]) * r + a[4]) * r + a[5]) *
141 ✔
50
        q /
51
        (((((b[0] * r + b[1]) * r + b[2]) * r + b[3]) * r + b[4]) * r + 1.0);
141 ✔
52

53
  } else {
54
    // Rational approximation for upper region
55

56
    q = std::sqrt(-2.0 * std::log(1.0 - p));
11 ✔
57
    z = -(((((c[0] * q + c[1]) * q + c[2]) * q + c[3]) * q + c[4]) * q + c[5]) /
11 ✔
58
        ((((d[0] * q + d[1]) * q + d[2]) * q + d[3]) * q + 1.0);
11 ✔
59
  }
60

61
  // Refinement based on Newton's method
62

63
  z = z - (0.5 * std::erfc(-z / std::sqrt(2.0)) - p) * std::sqrt(2.0 * PI) *
163 ✔
64
            std::exp(0.5 * z * z);
163 ✔
65

66
  return z;
163 ✔
67
}
68

69
double t_percentile(double p, int df)
303 ✔
70
{
71
  double t;
303 ✔
72

73
  if (df == 1) {
303 ✔
74
    // For one degree of freedom, the t-distribution becomes a Cauchy
75
    // distribution whose cdf we can invert directly
76

77
    t = std::tan(PI * (p - 0.5));
70 ✔
78
  } else if (df == 2) {
233 ✔
79
    // For two degrees of freedom, the cdf is given by 1/2 + x/(2*sqrt(x^2 +
80
    // 2)). This can be directly inverted to yield the solution below
81

82
    t = 2.0 * std::sqrt(2.0) * (p - 0.5) /
140 ✔
83
        std::sqrt(1. - 4. * std::pow(p - 0.5, 2.));
70 ✔
84
  } else {
85
    // This approximation is from E. Olusegun George and Meenakshi Sivaram, "A
86
    // modification of the Fisher-Cornish approximation for the student t
87
    // percentiles," Communication in Statistics - Simulation and Computation,
88
    // 16 (4), pp. 1123-1132 (1987).
89
    double n = df;
163 ✔
90
    double k = 1. / (n - 2.);
163 ✔
91
    double z = normal_percentile(p);
163 ✔
92
    double z2 = z * z;
163 ✔
93
    t = std::sqrt(n * k) *
163 ✔
94
        (z + (z2 - 3.) * z * k / 4. +
163 ✔
95
          ((5. * z2 - 56.) * z2 + 75.) * z * k * k / 96. +
163 ✔
96
          (((z2 - 27.) * 3. * z2 + 417.) * z2 - 315.) * z * k * k * k / 384.);
163 ✔
97
  }
98

99
  return t;
303 ✔
100
}
101

102
double standard_normal_cdf(double z)
110 ✔
103
{
104
  // Use the complementary error function to compute the standard normal CDF
105
  // Phi(z) = 0.5 * (1 + erf(z / sqrt(2))) = 0.5 * erfc(-z / sqrt(2))
106
  return 0.5 * std::erfc(-z / std::sqrt(2.0));
110 ✔
107
}
108

109
void calc_pn_c(int n, double x, double pnx[])
634,591,185 ✔
110
{
111
  pnx[0] = 1.;
634,591,185 ✔
112
  if (n >= 1) {
634,591,185 ✔
113
    pnx[1] = x;
144,845,151 ✔
114
  }
115

116
  // Use recursion relation to build the higher orders
117
  for (int l = 1; l < n; l++) {
640,733,156 ✔
118
    pnx[l + 1] = ((2 * l + 1) * x * pnx[l] - l * pnx[l - 1]) / (l + 1);
6,141,971 ✔
119
  }
120
}
634,591,185 ✔
121

122
double evaluate_legendre(int n, const double data[], double x)
127,558,640 ✔
123
{
124
  double* pnx = new double[n + 1];
127,558,640 !
125
  double val = 0.0;
127,558,640 ✔
126
  calc_pn_c(n, x, pnx);
127,558,640 ✔
127
  for (int l = 0; l <= n; l++) {
334,801,819 ✔
128
    val += (l + 0.5) * data[l] * pnx[l];
207,243,179 ✔
129
  }
130
  delete[] pnx;
127,558,640 ✔
131
  return val;
127,558,640 ✔
132
}
133

134
void calc_rn_c(int n, const double uvw[3], double rn[])
11 ✔
135
{
136
  Direction u {uvw};
11 ✔
137
  calc_rn(n, u, rn);
11 ✔
138
}
11 ✔
139

140
void calc_rn(int n, Direction u, double rn[])
4,568,344 ✔
141
{
142
  // rn[] is assumed to have already been allocated to the correct size
143

144
  // Store the cosine of the polar angle and the azimuthal angle
145
  double w = u.z;
4,568,344 ✔
146
  double phi;
4,568,344 ✔
147
  if (u.x == 0.) {
4,568,344 !
148
    phi = 0.;
149
  } else {
150
    phi = std::atan2(u.y, u.x);
4,568,344 ✔
151
  }
152

153
  // Store the shorthand of 1-w * w
154
  double w2m1 = 1. - w * w;
4,568,344 ✔
155

156
  // Now evaluate the spherical harmonics function
157
  rn[0] = 1.;
4,568,344 ✔
158
  int i = 0;
4,568,344 ✔
159
  for (int l = 1; l <= n; l++) {
22,844,778 ✔
160
    // Set the index to the start of this order
161
    i += 2 * (l - 1) + 1;
18,276,434 ✔
162

163
    // Now evaluate each
164
    switch (l) {
18,276,434 !
165
    case 1:
4,568,344 ✔
166
      // l = 1, m = -1
167
      rn[i] = -(std::sqrt(w2m1) * std::sin(phi));
4,568,344 ✔
168
      // l = 1, m = 0
169
      rn[i + 1] = w;
4,568,344 ✔
170
      // l = 1, m = 1
171
      rn[i + 2] = -(std::sqrt(w2m1) * std::cos(phi));
4,568,344 ✔
172
      break;
4,568,344 ✔
173
    case 2:
4,568,344 ✔
174
      // l = 2, m = -2
175
      rn[i] = 0.288675134594813 * (-3. * w * w + 3.) * std::sin(2. * phi);
4,568,344 ✔
176
      // l = 2, m = -1
177
      rn[i + 1] = -(1.73205080756888 * w * std::sqrt(w2m1) * std::sin(phi));
4,568,344 ✔
178
      // l = 2, m = 0
179
      rn[i + 2] = 1.5 * w * w - 0.5;
4,568,344 ✔
180
      // l = 2, m = 1
181
      rn[i + 3] = -(1.73205080756888 * w * std::sqrt(w2m1) * std::cos(phi));
4,568,344 ✔
182
      // l = 2, m = 2
183
      rn[i + 4] = 0.288675134594813 * (-3. * w * w + 3.) * std::cos(2. * phi);
4,568,344 ✔
184
      break;
4,568,344 ✔
185
    case 3:
4,568,344 ✔
186
      // l = 3, m = -3
187
      rn[i] = -(0.790569415042095 * std::pow(w2m1, 1.5) * std::sin(3. * phi));
4,568,344 ✔
188
      // l = 3, m = -2
189
      rn[i + 1] = 1.93649167310371 * w * (w2m1)*std::sin(2. * phi);
4,568,344 ✔
190
      // l = 3, m = -1
191
      rn[i + 2] = -(0.408248290463863 * std::sqrt(w2m1) *
4,568,344 ✔
192
                    ((7.5) * w * w - 3. / 2.) * std::sin(phi));
4,568,344 ✔
193
      // l = 3, m = 0
194
      rn[i + 3] = 2.5 * std::pow(w, 3) - 1.5 * w;
4,568,344 ✔
195
      // l = 3, m = 1
196
      rn[i + 4] = -(0.408248290463863 * std::sqrt(w2m1) *
4,568,344 ✔
197
                    ((7.5) * w * w - 3. / 2.) * std::cos(phi));
4,568,344 ✔
198
      // l = 3, m = 2
199
      rn[i + 5] = 1.93649167310371 * w * (w2m1)*std::cos(2. * phi);
4,568,344 ✔
200
      // l = 3, m = 3
201
      rn[i + 6] =
9,136,688 ✔
202
        -(0.790569415042095 * std::pow(w2m1, 1.5) * std::cos(3. * phi));
4,568,344 ✔
203
      break;
4,568,344 ✔
204
    case 4:
4,568,344 ✔
205
      // l = 4, m = -4
206
      rn[i] = 0.739509972887452 * (w2m1 * w2m1) * std::sin(4.0 * phi);
4,568,344 ✔
207
      // l = 4, m = -3
208
      rn[i + 1] =
9,136,688 ✔
209
        -(2.09165006633519 * w * std::pow(w2m1, 1.5) * std::sin(3. * phi));
4,568,344 ✔
210
      // l = 4, m = -2
211
      rn[i + 2] =
9,136,688 ✔
212
        0.074535599249993 * (w2m1) * (52.5 * w * w - 7.5) * std::sin(2. * phi);
4,568,344 ✔
213
      // l = 4, m = -1
214
      rn[i + 3] = -(0.316227766016838 * std::sqrt(w2m1) *
4,568,344 ✔
215
                    (17.5 * std::pow(w, 3) - 7.5 * w) * std::sin(phi));
4,568,344 ✔
216
      // l = 4, m = 0
217
      rn[i + 4] = 4.375 * std::pow(w, 4) - 3.75 * w * w + 0.375;
4,568,344 ✔
218
      // l = 4, m = 1
219
      rn[i + 5] = -(0.316227766016838 * std::sqrt(w2m1) *
4,568,344 ✔
220
                    (17.5 * std::pow(w, 3) - 7.5 * w) * std::cos(phi));
4,568,344 ✔
221
      // l = 4, m = 2
222
      rn[i + 6] =
9,136,688 ✔
223
        0.074535599249993 * (w2m1) * (52.5 * w * w - 7.5) * std::cos(2. * phi);
4,568,344 ✔
224
      // l = 4, m = 3
225
      rn[i + 7] =
9,136,688 ✔
226
        -(2.09165006633519 * w * std::pow(w2m1, 1.5) * std::cos(3. * phi));
4,568,344 ✔
227
      // l = 4, m = 4
228
      rn[i + 8] = 0.739509972887452 * w2m1 * w2m1 * std::cos(4.0 * phi);
4,568,344 ✔
229
      break;
4,568,344 ✔
230
    case 5:
3,003 ✔
231
      // l = 5, m = -5
232
      rn[i] = -(0.701560760020114 * std::pow(w2m1, 2.5) * std::sin(5.0 * phi));
3,003 ✔
233
      // l = 5, m = -4
234
      rn[i + 1] = 2.21852991866236 * w * w2m1 * w2m1 * std::sin(4.0 * phi);
3,003 ✔
235
      // l = 5, m = -3
236
      rn[i + 2] = -(0.00996023841111995 * std::pow(w2m1, 1.5) *
3,003 ✔
237
                    ((945.0 / 2.) * w * w - 52.5) * std::sin(3. * phi));
3,003 ✔
238
      // l = 5, m = -2
239
      rn[i + 3] = 0.0487950036474267 * (w2m1) *
3,003 ✔
240
                  ((315.0 / 2.) * std::pow(w, 3) - 52.5 * w) *
6,006 ✔
241
                  std::sin(2. * phi);
3,003 ✔
242
      // l = 5, m = -1
243
      rn[i + 4] =
6,006 ✔
244
        -(0.258198889747161 * std::sqrt(w2m1) *
3,003 ✔
245
          (39.375 * std::pow(w, 4) - 105.0 / 4.0 * w * w + 15.0 / 8.0) *
6,006 ✔
246
          std::sin(phi));
3,003 ✔
247
      // l = 5, m = 0
248
      rn[i + 5] = 7.875 * std::pow(w, 5) - 8.75 * std::pow(w, 3) + 1.875 * w;
3,003 ✔
249
      // l = 5, m = 1
250
      rn[i + 6] =
6,006 ✔
251
        -(0.258198889747161 * std::sqrt(w2m1) *
3,003 ✔
252
          (39.375 * std::pow(w, 4) - 105.0 / 4.0 * w * w + 15.0 / 8.0) *
6,006 ✔
253
          std::cos(phi));
3,003 ✔
254
      // l = 5, m = 2
255
      rn[i + 7] = 0.0487950036474267 * (w2m1) *
3,003 ✔
256
                  ((315.0 / 2.) * std::pow(w, 3) - 52.5 * w) *
6,006 ✔
257
                  std::cos(2. * phi);
3,003 ✔
258
      // l = 5, m = 3
259
      rn[i + 8] = -(0.00996023841111995 * std::pow(w2m1, 1.5) *
3,003 ✔
260
                    ((945.0 / 2.) * w * w - 52.5) * std::cos(3. * phi));
3,003 ✔
261
      // l = 5, m = 4
262
      rn[i + 9] = 2.21852991866236 * w * w2m1 * w2m1 * std::cos(4.0 * phi);
3,003 ✔
263
      // l = 5, m = 5
264
      rn[i + 10] =
6,006 ✔
265
        -(0.701560760020114 * std::pow(w2m1, 2.5) * std::cos(5.0 * phi));
3,003 ✔
266
      break;
3,003 ✔
267
    case 6:
11 ✔
268
      // l = 6, m = -6
269
      rn[i] = 0.671693289381396 * std::pow(w2m1, 3) * std::sin(6.0 * phi);
11 ✔
270
      // l = 6, m = -5
271
      rn[i + 1] =
22 ✔
272
        -(2.32681380862329 * w * std::pow(w2m1, 2.5) * std::sin(5.0 * phi));
11 ✔
273
      // l = 6, m = -4
274
      rn[i + 2] = 0.00104990131391452 * w2m1 * w2m1 *
22 ✔
275
                  ((10395.0 / 2.) * w * w - 945.0 / 2.) * std::sin(4.0 * phi);
11 ✔
276
      // l = 6, m = -3
277
      rn[i + 3] = -(0.00575054632785295 * std::pow(w2m1, 1.5) *
11 ✔
278
                    ((3465.0 / 2.) * std::pow(w, 3) - 945.0 / 2. * w) *
22 ✔
279
                    std::sin(3. * phi));
11 ✔
280
      // l = 6, m = -2
281
      rn[i + 4] =
22 ✔
282
        0.0345032779671177 * (w2m1) *
11 ✔
283
        ((3465.0 / 8.0) * std::pow(w, 4) - 945.0 / 4.0 * w * w + 105.0 / 8.0) *
22 ✔
284
        std::sin(2. * phi);
11 ✔
285
      // l = 6, m = -1
286
      rn[i + 5] = -(0.218217890235992 * std::sqrt(w2m1) *
11 ✔
287
                    ((693.0 / 8.0) * std::pow(w, 5) -
11 ✔
288
                      315.0 / 4.0 * std::pow(w, 3) + (105.0 / 8.0) * w) *
22 ✔
289
                    std::sin(phi));
11 ✔
290
      // l = 6, m = 0
291
      rn[i + 6] = 14.4375 * std::pow(w, 6) - 19.6875 * std::pow(w, 4) +
11 ✔
292
                  6.5625 * w * w - 0.3125;
11 ✔
293
      // l = 6, m = 1
294
      rn[i + 7] = -(0.218217890235992 * std::sqrt(w2m1) *
11 ✔
295
                    ((693.0 / 8.0) * std::pow(w, 5) -
11 ✔
296
                      315.0 / 4.0 * std::pow(w, 3) + (105.0 / 8.0) * w) *
22 ✔
297
                    std::cos(phi));
11 ✔
298
      // l = 6, m = 2
299
      rn[i + 8] =
22 ✔
300
        0.0345032779671177 * w2m1 *
11 ✔
301
        ((3465.0 / 8.0) * std::pow(w, 4) - 945.0 / 4.0 * w * w + 105.0 / 8.0) *
22 ✔
302
        std::cos(2. * phi);
11 ✔
303
      // l = 6, m = 3
304
      rn[i + 9] = -(0.00575054632785295 * std::pow(w2m1, 1.5) *
11 ✔
305
                    ((3465.0 / 2.) * std::pow(w, 3) - 945.0 / 2. * w) *
22 ✔
306
                    std::cos(3. * phi));
11 ✔
307
      // l = 6, m = 4
308
      rn[i + 10] = 0.00104990131391452 * w2m1 * w2m1 *
22 ✔
309
                   ((10395.0 / 2.) * w * w - 945.0 / 2.) * std::cos(4.0 * phi);
11 ✔
310
      // l = 6, m = 5
311
      rn[i + 11] =
22 ✔
312
        -(2.32681380862329 * w * std::pow(w2m1, 2.5) * std::cos(5.0 * phi));
11 ✔
313
      // l = 6, m = 6
314
      rn[i + 12] = 0.671693289381396 * std::pow(w2m1, 3) * std::cos(6.0 * phi);
11 ✔
315
      break;
11 ✔
316
    case 7:
11 ✔
317
      // l = 7, m = -7
318
      rn[i] = -(0.647259849287749 * std::pow(w2m1, 3.5) * std::sin(7.0 * phi));
11 ✔
319
      // l = 7, m = -6
320
      rn[i + 1] =
22 ✔
321
        2.42182459624969 * w * std::pow(w2m1, 3) * std::sin(6.0 * phi);
11 ✔
322
      // l = 7, m = -5
323
      rn[i + 2] =
22 ✔
324
        -(9.13821798555235e-5 * std::pow(w2m1, 2.5) *
11 ✔
325
          ((135135.0 / 2.) * w * w - 10395.0 / 2.) * std::sin(5.0 * phi));
11 ✔
326
      // l = 7, m = -4
327
      rn[i + 3] = 0.000548293079133141 * w2m1 * w2m1 *
11 ✔
328
                  ((45045.0 / 2.) * std::pow(w, 3) - 10395.0 / 2. * w) *
22 ✔
329
                  std::sin(4.0 * phi);
11 ✔
330
      // l = 7, m = -3
331
      rn[i + 4] = -(0.00363696483726654 * std::pow(w2m1, 1.5) *
11 ✔
332
                    ((45045.0 / 8.0) * std::pow(w, 4) - 10395.0 / 4.0 * w * w +
11 ✔
333
                      945.0 / 8.0) *
11 ✔
334
                    std::sin(3. * phi));
11 ✔
335
      // l = 7, m = -2
336
      rn[i + 5] = 0.025717224993682 * (w2m1) *
11 ✔
337
                  ((9009.0 / 8.0) * std::pow(w, 5) -
11 ✔
338
                    3465.0 / 4.0 * std::pow(w, 3) + (945.0 / 8.0) * w) *
22 ✔
339
                  std::sin(2. * phi);
11 ✔
340
      // l = 7, m = -1
341
      rn[i + 6] =
22 ✔
342
        -(0.188982236504614 * std::sqrt(w2m1) *
11 ✔
343
          ((3003.0 / 16.0) * std::pow(w, 6) - 3465.0 / 16.0 * std::pow(w, 4) +
11 ✔
344
            (945.0 / 16.0) * w * w - 35.0 / 16.0) *
22 ✔
345
          std::sin(phi));
11 ✔
346
      // l = 7, m = 0
347
      rn[i + 7] = 26.8125 * std::pow(w, 7) - 43.3125 * std::pow(w, 5) +
11 ✔
348
                  19.6875 * std::pow(w, 3) - 2.1875 * w;
11 ✔
349
      // l = 7, m = 1
350
      rn[i + 8] =
22 ✔
351
        -(0.188982236504614 * std::sqrt(w2m1) *
11 ✔
352
          ((3003.0 / 16.0) * std::pow(w, 6) - 3465.0 / 16.0 * std::pow(w, 4) +
11 ✔
353
            (945.0 / 16.0) * w * w - 35.0 / 16.0) *
22 ✔
354
          std::cos(phi));
11 ✔
355
      // l = 7, m = 2
356
      rn[i + 9] = 0.025717224993682 * (w2m1) *
11 ✔
357
                  ((9009.0 / 8.0) * std::pow(w, 5) -
11 ✔
358
                    3465.0 / 4.0 * std::pow(w, 3) + (945.0 / 8.0) * w) *
22 ✔
359
                  std::cos(2. * phi);
11 ✔
360
      // l = 7, m = 3
361
      rn[i + 10] = -(0.00363696483726654 * std::pow(w2m1, 1.5) *
11 ✔
362
                     ((45045.0 / 8.0) * std::pow(w, 4) - 10395.0 / 4.0 * w * w +
11 ✔
363
                       945.0 / 8.0) *
11 ✔
364
                     std::cos(3. * phi));
11 ✔
365
      // l = 7, m = 4
366
      rn[i + 11] = 0.000548293079133141 * w2m1 * w2m1 *
11 ✔
367
                   ((45045.0 / 2.) * std::pow(w, 3) - 10395.0 / 2. * w) *
22 ✔
368
                   std::cos(4.0 * phi);
11 ✔
369
      // l = 7, m = 5
370
      rn[i + 12] =
22 ✔
371
        -(9.13821798555235e-5 * std::pow(w2m1, 2.5) *
11 ✔
372
          ((135135.0 / 2.) * w * w - 10395.0 / 2.) * std::cos(5.0 * phi));
11 ✔
373
      // l = 7, m = 6
374
      rn[i + 13] =
22 ✔
375
        2.42182459624969 * w * std::pow(w2m1, 3) * std::cos(6.0 * phi);
11 ✔
376
      // l = 7, m = 7
377
      rn[i + 14] =
22 ✔
378
        -(0.647259849287749 * std::pow(w2m1, 3.5) * std::cos(7.0 * phi));
11 ✔
379
      break;
11 ✔
380
    case 8:
11 ✔
381
      // l = 8, m = -8
382
      rn[i] = 0.626706654240044 * std::pow(w2m1, 4) * std::sin(8.0 * phi);
11 ✔
383
      // l = 8, m = -7
384
      rn[i + 1] =
22 ✔
385
        -(2.50682661696018 * w * std::pow(w2m1, 3.5) * std::sin(7.0 * phi));
11 ✔
386
      // l = 8, m = -6
387
      rn[i + 2] = 6.77369783729086e-6 * std::pow(w2m1, 3) *
11 ✔
388
                  ((2027025.0 / 2.) * w * w - 135135.0 / 2.) *
22 ✔
389
                  std::sin(6.0 * phi);
11 ✔
390
      // l = 8, m = -5
391
      rn[i + 3] = -(4.38985792528482e-5 * std::pow(w2m1, 2.5) *
11 ✔
392
                    ((675675.0 / 2.) * std::pow(w, 3) - 135135.0 / 2. * w) *
22 ✔
393
                    std::sin(5.0 * phi));
11 ✔
394
      // l = 8, m = -4
395
      rn[i + 4] = 0.000316557156832328 * w2m1 * w2m1 *
11 ✔
396
                  ((675675.0 / 8.0) * std::pow(w, 4) - 135135.0 / 4.0 * w * w +
11 ✔
397
                    10395.0 / 8.0) *
11 ✔
398
                  std::sin(4.0 * phi);
11 ✔
399
      // l = 8, m = -3
400
      rn[i + 5] = -(0.00245204119306875 * std::pow(w2m1, 1.5) *
11 ✔
401
                    ((135135.0 / 8.0) * std::pow(w, 5) -
11 ✔
402
                      45045.0 / 4.0 * std::pow(w, 3) + (10395.0 / 8.0) * w) *
22 ✔
403
                    std::sin(3. * phi));
11 ✔
404
      // l = 8, m = -2
405
      rn[i + 6] =
22 ✔
406
        0.0199204768222399 * (w2m1) *
11 ✔
407
        ((45045.0 / 16.0) * std::pow(w, 6) - 45045.0 / 16.0 * std::pow(w, 4) +
11 ✔
408
          (10395.0 / 16.0) * w * w - 315.0 / 16.0) *
22 ✔
409
        std::sin(2. * phi);
11 ✔
410
      // l = 8, m = -1
411
      rn[i + 7] =
22 ✔
412
        -(0.166666666666667 * std::sqrt(w2m1) *
11 ✔
413
          ((6435.0 / 16.0) * std::pow(w, 7) - 9009.0 / 16.0 * std::pow(w, 5) +
11 ✔
414
            (3465.0 / 16.0) * std::pow(w, 3) - 315.0 / 16.0 * w) *
22 ✔
415
          std::sin(phi));
11 ✔
416
      // l = 8, m = 0
417
      rn[i + 8] = 50.2734375 * std::pow(w, 8) - 93.84375 * std::pow(w, 6) +
11 ✔
418
                  54.140625 * std::pow(w, 4) - 9.84375 * w * w + 0.2734375;
11 ✔
419
      // l = 8, m = 1
420
      rn[i + 9] =
22 ✔
421
        -(0.166666666666667 * std::sqrt(w2m1) *
11 ✔
422
          ((6435.0 / 16.0) * std::pow(w, 7) - 9009.0 / 16.0 * std::pow(w, 5) +
11 ✔
423
            (3465.0 / 16.0) * std::pow(w, 3) - 315.0 / 16.0 * w) *
22 ✔
424
          std::cos(phi));
11 ✔
425
      // l = 8, m = 2
426
      rn[i + 10] =
22 ✔
427
        0.0199204768222399 * (w2m1) *
11 ✔
428
        ((45045.0 / 16.0) * std::pow(w, 6) - 45045.0 / 16.0 * std::pow(w, 4) +
11 ✔
429
          (10395.0 / 16.0) * w * w - 315.0 / 16.0) *
22 ✔
430
        std::cos(2. * phi);
11 ✔
431
      // l = 8, m = 3
432
      rn[i + 11] = -(0.00245204119306875 * std::pow(w2m1, 1.5) *
11 ✔
433
                     ((135135.0 / 8.0) * std::pow(w, 5) -
11 ✔
434
                       45045.0 / 4.0 * std::pow(w, 3) + (10395.0 / 8.0) * w) *
22 ✔
435
                     std::cos(3. * phi));
11 ✔
436
      // l = 8, m = 4
437
      rn[i + 12] = 0.000316557156832328 * w2m1 * w2m1 *
11 ✔
438
                   ((675675.0 / 8.0) * std::pow(w, 4) - 135135.0 / 4.0 * w * w +
11 ✔
439
                     10395.0 / 8.0) *
11 ✔
440
                   std::cos(4.0 * phi);
11 ✔
441
      // l = 8, m = 5
442
      rn[i + 13] = -(4.38985792528482e-5 * std::pow(w2m1, 2.5) *
11 ✔
443
                     ((675675.0 / 2.) * std::pow(w, 3) - 135135.0 / 2. * w) *
22 ✔
444
                     std::cos(5.0 * phi));
11 ✔
445
      // l = 8, m = 6
446
      rn[i + 14] = 6.77369783729086e-6 * std::pow(w2m1, 3) *
11 ✔
447
                   ((2027025.0 / 2.) * w * w - 135135.0 / 2.) *
11 ✔
448
                   std::cos(6.0 * phi);
11 ✔
449
      // l = 8, m = 7
450
      rn[i + 15] =
22 ✔
451
        -(2.50682661696018 * w * std::pow(w2m1, 3.5) * std::cos(7.0 * phi));
11 ✔
452
      // l = 8, m = 8
453
      rn[i + 16] = 0.626706654240044 * std::pow(w2m1, 4) * std::cos(8.0 * phi);
11 ✔
454
      break;
11 ✔
455
    case 9:
11 ✔
456
      // l = 9, m = -9
457
      rn[i] = -(0.609049392175524 * std::pow(w2m1, 4.5) * std::sin(9.0 * phi));
11 ✔
458
      // l = 9, m = -8
459
      rn[i + 1] =
22 ✔
460
        2.58397773170915 * w * std::pow(w2m1, 4) * std::sin(8.0 * phi);
11 ✔
461
      // l = 9, m = -7
462
      rn[i + 2] =
22 ✔
463
        -(4.37240315267812e-7 * std::pow(w2m1, 3.5) *
11 ✔
464
          ((34459425.0 / 2.) * w * w - 2027025.0 / 2.) * std::sin(7.0 * phi));
11 ✔
465
      // l = 9, m = -6
466
      rn[i + 3] = 3.02928976464514e-6 * std::pow(w2m1, 3) *
11 ✔
467
                  ((11486475.0 / 2.) * std::pow(w, 3) - 2027025.0 / 2. * w) *
22 ✔
468
                  std::sin(6.0 * phi);
11 ✔
469
      // l = 9, m = -5
470
      rn[i + 4] = -(2.34647776186144e-5 * std::pow(w2m1, 2.5) *
11 ✔
471
                    ((11486475.0 / 8.0) * std::pow(w, 4) -
11 ✔
472
                      2027025.0 / 4.0 * w * w + 135135.0 / 8.0) *
22 ✔
473
                    std::sin(5.0 * phi));
11 ✔
474
      // l = 9, m = -4
475
      rn[i + 5] = 0.000196320414650061 * w2m1 * w2m1 *
11 ✔
476
                  ((2297295.0 / 8.0) * std::pow(w, 5) -
11 ✔
477
                    675675.0 / 4.0 * std::pow(w, 3) + (135135.0 / 8.0) * w) *
22 ✔
478
                  std::sin(4.0 * phi);
11 ✔
479
      // l = 9, m = -3
480
      rn[i + 6] = -(
22 ✔
481
        0.00173385495536766 * std::pow(w2m1, 1.5) *
11 ✔
482
        ((765765.0 / 16.0) * std::pow(w, 6) - 675675.0 / 16.0 * std::pow(w, 4) +
11 ✔
483
          (135135.0 / 16.0) * w * w - 3465.0 / 16.0) *
22 ✔
484
        std::sin(3. * phi));
11 ✔
485
      // l = 9, m = -2
486
      rn[i + 7] =
22 ✔
487
        0.0158910431540932 * (w2m1) *
11 ✔
488
        ((109395.0 / 16.0) * std::pow(w, 7) - 135135.0 / 16.0 * std::pow(w, 5) +
11 ✔
489
          (45045.0 / 16.0) * std::pow(w, 3) - 3465.0 / 16.0 * w) *
22 ✔
490
        std::sin(2. * phi);
11 ✔
491
      // l = 9, m = -1
492
      rn[i + 8] = -(
22 ✔
493
        0.149071198499986 * std::sqrt(w2m1) *
11 ✔
494
        ((109395.0 / 128.0) * std::pow(w, 8) - 45045.0 / 32.0 * std::pow(w, 6) +
11 ✔
495
          (45045.0 / 64.0) * std::pow(w, 4) - 3465.0 / 32.0 * w * w +
11 ✔
496
          315.0 / 128.0) *
11 ✔
497
        std::sin(phi));
11 ✔
498
      // l = 9, m = 0
499
      rn[i + 9] = 94.9609375 * std::pow(w, 9) - 201.09375 * std::pow(w, 7) +
11 ✔
500
                  140.765625 * std::pow(w, 5) - 36.09375 * std::pow(w, 3) +
11 ✔
501
                  2.4609375 * w;
11 ✔
502
      // l = 9, m = 1
503
      rn[i + 10] = -(
22 ✔
504
        0.149071198499986 * std::sqrt(w2m1) *
11 ✔
505
        ((109395.0 / 128.0) * std::pow(w, 8) - 45045.0 / 32.0 * std::pow(w, 6) +
11 ✔
506
          (45045.0 / 64.0) * std::pow(w, 4) - 3465.0 / 32.0 * w * w +
11 ✔
507
          315.0 / 128.0) *
11 ✔
508
        std::cos(phi));
11 ✔
509
      // l = 9, m = 2
510
      rn[i + 11] =
22 ✔
511
        0.0158910431540932 * (w2m1) *
11 ✔
512
        ((109395.0 / 16.0) * std::pow(w, 7) - 135135.0 / 16.0 * std::pow(w, 5) +
11 ✔
513
          (45045.0 / 16.0) * std::pow(w, 3) - 3465.0 / 16.0 * w) *
22 ✔
514
        std::cos(2. * phi);
11 ✔
515
      // l = 9, m = 3
516
      rn[i + 12] = -(
22 ✔
517
        0.00173385495536766 * std::pow(w2m1, 1.5) *
11 ✔
518
        ((765765.0 / 16.0) * std::pow(w, 6) - 675675.0 / 16.0 * std::pow(w, 4) +
11 ✔
519
          (135135.0 / 16.0) * w * w - 3465.0 / 16.0) *
22 ✔
520
        std::cos(3. * phi));
11 ✔
521
      // l = 9, m = 4
522
      rn[i + 13] = 0.000196320414650061 * w2m1 * w2m1 *
11 ✔
523
                   ((2297295.0 / 8.0) * std::pow(w, 5) -
11 ✔
524
                     675675.0 / 4.0 * std::pow(w, 3) + (135135.0 / 8.0) * w) *
22 ✔
525
                   std::cos(4.0 * phi);
11 ✔
526
      // l = 9, m = 5
527
      rn[i + 14] = -(2.34647776186144e-5 * std::pow(w2m1, 2.5) *
11 ✔
528
                     ((11486475.0 / 8.0) * std::pow(w, 4) -
11 ✔
529
                       2027025.0 / 4.0 * w * w + 135135.0 / 8.0) *
22 ✔
530
                     std::cos(5.0 * phi));
11 ✔
531
      // l = 9, m = 6
532
      rn[i + 15] = 3.02928976464514e-6 * std::pow(w2m1, 3) *
11 ✔
533
                   ((11486475.0 / 2.) * std::pow(w, 3) - 2027025.0 / 2. * w) *
22 ✔
534
                   std::cos(6.0 * phi);
11 ✔
535
      // l = 9, m = 7
536
      rn[i + 16] =
22 ✔
537
        -(4.37240315267812e-7 * std::pow(w2m1, 3.5) *
11 ✔
538
          ((34459425.0 / 2.) * w * w - 2027025.0 / 2.) * std::cos(7.0 * phi));
11 ✔
539
      // l = 9, m = 8
540
      rn[i + 17] =
22 ✔
541
        2.58397773170915 * w * std::pow(w2m1, 4) * std::cos(8.0 * phi);
11 ✔
542
      // l = 9, m = 9
543
      rn[i + 18] =
22 ✔
544
        -(0.609049392175524 * std::pow(w2m1, 4.5) * std::cos(9.0 * phi));
11 ✔
545
      break;
11 ✔
546
    case 10:
11 ✔
547
      // l = 10, m = -10
548
      rn[i] = 0.593627917136573 * std::pow(w2m1, 5) * std::sin(10.0 * phi);
11 ✔
549
      // l = 10, m = -9
550
      rn[i + 1] =
22 ✔
551
        -(2.65478475211798 * w * std::pow(w2m1, 4.5) * std::sin(9.0 * phi));
11 ✔
552
      // l = 10, m = -8
553
      rn[i + 2] = 2.49953651452314e-8 * std::pow(w2m1, 4) *
11 ✔
554
                  ((654729075.0 / 2.) * w * w - 34459425.0 / 2.) *
22 ✔
555
                  std::sin(8.0 * phi);
11 ✔
556
      // l = 10, m = -7
557
      rn[i + 3] =
22 ✔
558
        -(1.83677671621093e-7 * std::pow(w2m1, 3.5) *
11 ✔
559
          ((218243025.0 / 2.) * std::pow(w, 3) - 34459425.0 / 2. * w) *
22 ✔
560
          std::sin(7.0 * phi));
11 ✔
561
      // l = 10, m = -6
562
      rn[i + 4] = 1.51464488232257e-6 * std::pow(w2m1, 3) *
11 ✔
563
                  ((218243025.0 / 8.0) * std::pow(w, 4) -
11 ✔
564
                    34459425.0 / 4.0 * w * w + 2027025.0 / 8.0) *
22 ✔
565
                  std::sin(6.0 * phi);
11 ✔
566
      // l = 10, m = -5
567
      rn[i + 5] =
22 ✔
568
        -(1.35473956745817e-5 * std::pow(w2m1, 2.5) *
11 ✔
569
          ((43648605.0 / 8.0) * std::pow(w, 5) -
11 ✔
570
            11486475.0 / 4.0 * std::pow(w, 3) + (2027025.0 / 8.0) * w) *
22 ✔
571
          std::sin(5.0 * phi));
11 ✔
572
      // l = 10, m = -4
573
      rn[i + 6] = 0.000128521880085575 * w2m1 * w2m1 *
11 ✔
574
                  ((14549535.0 / 16.0) * std::pow(w, 6) -
11 ✔
575
                    11486475.0 / 16.0 * std::pow(w, 4) +
11 ✔
576
                    (2027025.0 / 16.0) * w * w - 45045.0 / 16.0) *
22 ✔
577
                  std::sin(4.0 * phi);
11 ✔
578
      // l = 10, m = -3
579
      rn[i + 7] = -(0.00127230170115096 * std::pow(w2m1, 1.5) *
11 ✔
580
                    ((2078505.0 / 16.0) * std::pow(w, 7) -
11 ✔
581
                      2297295.0 / 16.0 * std::pow(w, 5) +
11 ✔
582
                      (675675.0 / 16.0) * std::pow(w, 3) - 45045.0 / 16.0 * w) *
22 ✔
583
                    std::sin(3. * phi));
11 ✔
584
      // l = 10, m = -2
585
      rn[i + 8] = 0.012974982402692 * (w2m1) *
11 ✔
586
                  ((2078505.0 / 128.0) * std::pow(w, 8) -
11 ✔
587
                    765765.0 / 32.0 * std::pow(w, 6) +
11 ✔
588
                    (675675.0 / 64.0) * std::pow(w, 4) -
11 ✔
589
                    45045.0 / 32.0 * w * w + 3465.0 / 128.0) *
22 ✔
590
                  std::sin(2. * phi);
11 ✔
591
      // l = 10, m = -1
592
      rn[i + 9] = -(0.134839972492648 * std::sqrt(w2m1) *
11 ✔
593
                    ((230945.0 / 128.0) * std::pow(w, 9) -
11 ✔
594
                      109395.0 / 32.0 * std::pow(w, 7) +
11 ✔
595
                      (135135.0 / 64.0) * std::pow(w, 5) -
11 ✔
596
                      15015.0 / 32.0 * std::pow(w, 3) + (3465.0 / 128.0) * w) *
22 ✔
597
                    std::sin(phi));
11 ✔
598
      // l = 10, m = 0
599
      rn[i + 10] = 180.42578125 * std::pow(w, 10) -
11 ✔
600
                   427.32421875 * std::pow(w, 8) +
11 ✔
601
                   351.9140625 * std::pow(w, 6) - 117.3046875 * std::pow(w, 4) +
11 ✔
602
                   13.53515625 * w * w - 0.24609375;
11 ✔
603
      // l = 10, m = 1
604
      rn[i + 11] = -(0.134839972492648 * std::sqrt(w2m1) *
11 ✔
605
                     ((230945.0 / 128.0) * std::pow(w, 9) -
11 ✔
606
                       109395.0 / 32.0 * std::pow(w, 7) +
11 ✔
607
                       (135135.0 / 64.0) * std::pow(w, 5) -
11 ✔
608
                       15015.0 / 32.0 * std::pow(w, 3) + (3465.0 / 128.0) * w) *
22 ✔
609
                     std::cos(phi));
11 ✔
610
      // l = 10, m = 2
611
      rn[i + 12] = 0.012974982402692 * (w2m1) *
11 ✔
612
                   ((2078505.0 / 128.0) * std::pow(w, 8) -
11 ✔
613
                     765765.0 / 32.0 * std::pow(w, 6) +
11 ✔
614
                     (675675.0 / 64.0) * std::pow(w, 4) -
11 ✔
615
                     45045.0 / 32.0 * w * w + 3465.0 / 128.0) *
22 ✔
616
                   std::cos(2. * phi);
11 ✔
617
      // l = 10, m = 3
618
      rn[i + 13] =
22 ✔
619
        -(0.00127230170115096 * std::pow(w2m1, 1.5) *
11 ✔
620
          ((2078505.0 / 16.0) * std::pow(w, 7) -
11 ✔
621
            2297295.0 / 16.0 * std::pow(w, 5) +
11 ✔
622
            (675675.0 / 16.0) * std::pow(w, 3) - 45045.0 / 16.0 * w) *
22 ✔
623
          std::cos(3. * phi));
11 ✔
624
      // l = 10, m = 4
625
      rn[i + 14] = 0.000128521880085575 * w2m1 * w2m1 *
11 ✔
626
                   ((14549535.0 / 16.0) * std::pow(w, 6) -
11 ✔
627
                     11486475.0 / 16.0 * std::pow(w, 4) +
11 ✔
628
                     (2027025.0 / 16.0) * w * w - 45045.0 / 16.0) *
22 ✔
629
                   std::cos(4.0 * phi);
11 ✔
630
      // l = 10, m = 5
631
      rn[i + 15] =
22 ✔
632
        -(1.35473956745817e-5 * std::pow(w2m1, 2.5) *
11 ✔
633
          ((43648605.0 / 8.0) * std::pow(w, 5) -
11 ✔
634
            11486475.0 / 4.0 * std::pow(w, 3) + (2027025.0 / 8.0) * w) *
22 ✔
635
          std::cos(5.0 * phi));
11 ✔
636
      // l = 10, m = 6
637
      rn[i + 16] = 1.51464488232257e-6 * std::pow(w2m1, 3) *
11 ✔
638
                   ((218243025.0 / 8.0) * std::pow(w, 4) -
11 ✔
639
                     34459425.0 / 4.0 * w * w + 2027025.0 / 8.0) *
22 ✔
640
                   std::cos(6.0 * phi);
11 ✔
641
      // l = 10, m = 7
642
      rn[i + 17] =
22 ✔
643
        -(1.83677671621093e-7 * std::pow(w2m1, 3.5) *
11 ✔
644
          ((218243025.0 / 2.) * std::pow(w, 3) - 34459425.0 / 2. * w) *
22 ✔
645
          std::cos(7.0 * phi));
11 ✔
646
      // l = 10, m = 8
647
      rn[i + 18] = 2.49953651452314e-8 * std::pow(w2m1, 4) *
11 ✔
648
                   ((654729075.0 / 2.) * w * w - 34459425.0 / 2.) *
11 ✔
649
                   std::cos(8.0 * phi);
11 ✔
650
      // l = 10, m = 9
651
      rn[i + 19] =
22 ✔
652
        -(2.65478475211798 * w * std::pow(w2m1, 4.5) * std::cos(9.0 * phi));
11 ✔
653
      // l = 10, m = 10
654
      rn[i + 20] = 0.593627917136573 * std::pow(w2m1, 5) * std::cos(10.0 * phi);
11 ✔
655
    }
656
  }
657
}
4,568,344 ✔
658

659
void calc_zn(int n, double rho, double phi, double zn[])
2,704,570 ✔
660
{
661
  // ===========================================================================
662
  // Determine vector of sin(n*phi) and cos(n*phi). This takes advantage of the
663
  // following recurrence relations so that only a single sin/cos have to be
664
  // evaluated (https://mathworld.wolfram.com/Multiple-AngleFormulas.html)
665
  //
666
  // sin(nx) = 2 cos(x) sin((n-1)x) - sin((n-2)x)
667
  // cos(nx) = 2 cos(x) cos((n-1)x) - cos((n-2)x)
668

669
  double sin_phi = std::sin(phi);
2,704,570 ✔
670
  double cos_phi = std::cos(phi);
2,704,570 ✔
671

672
  vector<double> sin_phi_vec(n + 1); // Sin[n * phi]
2,704,570 ✔
673
  vector<double> cos_phi_vec(n + 1); // Cos[n * phi]
2,704,570 ✔
674
  sin_phi_vec[0] = 1.0;
2,704,570 ✔
675
  cos_phi_vec[0] = 1.0;
2,704,570 ✔
676
  sin_phi_vec[1] = 2.0 * cos_phi;
2,704,570 ✔
677
  cos_phi_vec[1] = cos_phi;
2,704,570 ✔
678

679
  for (int i = 2; i <= n; i++) {
13,519,715 ✔
680
    sin_phi_vec[i] = 2. * cos_phi * sin_phi_vec[i - 1] - sin_phi_vec[i - 2];
10,815,145 ✔
681
    cos_phi_vec[i] = 2. * cos_phi * cos_phi_vec[i - 1] - cos_phi_vec[i - 2];
10,815,145 ✔
682
  }
683

684
  for (int i = 0; i <= n; i++) {
18,928,855 ✔
685
    sin_phi_vec[i] *= sin_phi;
16,224,285 ✔
686
  }
687

688
  // ===========================================================================
689
  // Calculate R_pq(rho)
690
  // Matrix forms of the coefficients which are easier to work with
691
  vector<vector<double>> zn_mat(n + 1, vector<double>(n + 1));
4,425,660 ✔
692

693
  // Fill the main diagonal first (Eq 3.9 in Chong)
694
  for (int p = 0; p <= n; p++) {
18,928,855 ✔
695
    zn_mat[p][p] = std::pow(rho, p);
16,224,285 ✔
696
  }
697

698
  // Fill the 2nd diagonal (Eq 3.10 in Chong)
699
  for (int q = 0; q <= n - 2; q++) {
13,519,715 ✔
700
    zn_mat[q][q + 2] = (q + 2) * zn_mat[q + 2][q + 2] - (q + 1) * zn_mat[q][q];
10,815,145 ✔
701
  }
702

703
  // Fill in the rest of the values using the original results (Eq. 3.8 in
704
  // Chong)
705
  for (int p = 4; p <= n; p++) {
8,110,575 ✔
706
    double k2 = 2 * p * (p - 1) * (p - 2);
5,406,005 ✔
707
    for (int q = p - 4; q >= 0; q -= 2) {
10,812,109 ✔
708
      double k1 = ((p + q) * (p - q) * (p - 2)) / 2.;
5,406,104 ✔
709
      double k3 = -q * q * (p - 1) - p * (p - 1) * (p - 2);
5,406,104 ✔
710
      double k4 = (-p * (p + q - 2) * (p - q - 2)) / 2.;
5,406,104 ✔
711
      zn_mat[q][p] =
5,406,104 ✔
712
        ((k2 * rho * rho + k3) * zn_mat[q][p - 2] + k4 * zn_mat[q][p - 4]) / k1;
5,406,104 ✔
713
    }
714
  }
715

716
  // Roll into a single vector for easier computation later
717
  // The vector is ordered (0,0), (1,-1), (1,1), (2,-2), (2,0),
718
  // (2, 2), ....   in (n,m) indices
719
  // Note that the cos and sin vectors are offset by one
720
  // sin_phi_vec = [sin(x), sin(2x), sin(3x) ...]
721
  // cos_phi_vec = [1.0, cos(x), cos(2x)... ]
722
  int i = 0;
723
  for (int p = 0; p <= n; p++) {
18,928,855 ✔
724
    for (int q = -p; q <= p; q += 2) {
73,003,106 ✔
725
      if (q < 0) {
56,778,821 ✔
726
        zn[i] = zn_mat[std::abs(q)][p] * sin_phi_vec[std::abs(q) - 1];
24,333,287 ✔
727
      } else if (q == 0) {
32,445,534 ✔
728
        zn[i] = zn_mat[q][p];
8,112,247 ✔
729
      } else {
730
        zn[i] = zn_mat[q][p] * cos_phi_vec[q];
24,333,287 ✔
731
      }
732
      i++;
56,778,821 ✔
733
    }
734
  }
735
}
2,704,570 ✔
736

737
void calc_zn_rad(int n, double rho, double zn_rad[])
44 ✔
738
{
739
  // Calculate R_p0(rho) as Zn_p0(rho)
740
  // Set up the array of the coefficients
741

742
  double q = 0;
44 ✔
743

744
  // R_00 is always 1
745
  zn_rad[0] = 1;
44 ✔
746

747
  // Fill in the rest of the array (Eq 3.8 and Eq 3.10 in Chong)
748
  for (int p = 2; p <= n; p += 2) {
264 ✔
749
    int index = int(p / 2);
220 ✔
750
    if (p == 2) {
220 ✔
751
      // Setting up R_22 to calculate R_20 (Eq 3.10 in Chong)
752
      double R_22 = rho * rho;
44 ✔
753
      zn_rad[index] = 2 * R_22 - zn_rad[0];
44 ✔
754
    } else {
755
      double k1 = ((p + q) * (p - q) * (p - 2)) / 2.;
176 ✔
756
      double k2 = 2 * p * (p - 1) * (p - 2);
176 ✔
757
      double k3 = -q * q * (p - 1) - p * (p - 1) * (p - 2);
176 ✔
758
      double k4 = (-p * (p + q - 2) * (p - q - 2)) / 2.;
176 ✔
759
      zn_rad[index] =
176 ✔
760
        ((k2 * rho * rho + k3) * zn_rad[index - 1] + k4 * zn_rad[index - 2]) /
176 ✔
761
        k1;
762
    }
763
  }
764
}
44 ✔
765

766
void rotate_angle_c(double uvw[3], double mu, const double* phi, uint64_t* seed)
33 ✔
767
{
768
  Direction u = rotate_angle({uvw}, mu, phi, seed);
33 ✔
769
  uvw[0] = u.x;
33 ✔
770
  uvw[1] = u.y;
33 ✔
771
  uvw[2] = u.z;
33 ✔
772
}
33 ✔
773

774
Direction rotate_angle(
2,147,483,647 ✔
775
  Direction u, double mu, const double* phi, uint64_t* seed)
776
{
777
  // Sample azimuthal angle in [0,2pi) if none provided
778
  double phi_;
2,147,483,647 ✔
779
  if (phi != nullptr) {
2,147,483,647 ✔
780
    phi_ = (*phi);
49,164,912 ✔
781
  } else {
782
    phi_ = 2.0 * PI * prn(seed);
2,147,483,647 ✔
783
  }
784

785
  // Precompute factors to save flops
786
  double sinphi = std::sin(phi_);
2,147,483,647 ✔
787
  double cosphi = std::cos(phi_);
2,147,483,647 ✔
788
  double a = std::sqrt(std::fmax(0., 1. - mu * mu));
2,147,483,647 ✔
789
  double b = std::sqrt(std::fmax(0., 1. - u.z * u.z));
2,147,483,647 ✔
790

791
  // Need to treat special case where sqrt(1 - w**2) is close to zero by
792
  // expanding about the v component rather than the w component
793
  if (b > 1e-10) {
2,147,483,647 ✔
794
    return {mu * u.x + a * (u.x * u.z * cosphi - u.y * sinphi) / b,
2,147,483,647 ✔
795
      mu * u.y + a * (u.y * u.z * cosphi + u.x * sinphi) / b,
2,147,483,647 ✔
796
      mu * u.z - a * b * cosphi};
2,147,483,647 ✔
797
  } else {
798
    b = std::sqrt(1. - u.y * u.y);
391,457 ✔
799
    return {mu * u.x + a * (-u.x * u.y * sinphi + u.z * cosphi) / b,
391,457 ✔
800
      mu * u.y + a * b * sinphi,
391,457 ✔
801
      mu * u.z - a * (u.y * u.z * sinphi + u.x * cosphi) / b};
391,457 ✔
802
  }
803
}
804

805
void spline(int n, const double x[], const double y[], double z[])
196,560 ✔
806
{
807
  vector<double> c_new(n - 1);
196,560 ✔
808

809
  // Set natural boundary conditions
810
  c_new[0] = 0.0;
196,560 ✔
811
  z[0] = 0.0;
196,560 ✔
812
  z[n - 1] = 0.0;
196,560 ✔
813

814
  // Solve using tridiagonal matrix algorithm; first do forward sweep
815
  for (int i = 1; i < n - 1; i++) {
19,731,104 ✔
816
    double a = x[i] - x[i - 1];
19,534,544 ✔
817
    double c = x[i + 1] - x[i];
19,534,544 ✔
818
    double b = 2.0 * (a + c);
19,534,544 ✔
819
    double d = 6.0 * ((y[i + 1] - y[i]) / c - (y[i] - y[i - 1]) / a);
19,534,544 ✔
820

821
    c_new[i] = c / (b - a * c_new[i - 1]);
19,534,544 ✔
822
    z[i] = (d - a * z[i - 1]) / (b - a * c_new[i - 1]);
19,534,544 ✔
823
  }
824

825
  // Back substitution
826
  for (int i = n - 2; i >= 0; i--) {
19,927,664 ✔
827
    z[i] = z[i] - c_new[i] * z[i + 1];
19,731,104 ✔
828
  }
829
}
196,560 ✔
830

UNCOV
831
double spline_interpolate(
×
832
  int n, const double x[], const double y[], const double z[], double xint)
833
{
834
  // Find the lower bounding index in x of xint
UNCOV
835
  int i = n - 1;
×
UNCOV
836
  while (--i) {
×
837
    if (xint >= x[i])
×
838
      break;
839
  }
840

UNCOV
841
  double h = x[i + 1] - x[i];
×
UNCOV
842
  double r = xint - x[i];
×
843

844
  // Compute the coefficients
UNCOV
845
  double b = (y[i + 1] - y[i]) / h - (h / 6.0) * (z[i + 1] + 2.0 * z[i]);
×
UNCOV
846
  double c = z[i] / 2.0;
×
847
  double d = (z[i + 1] - z[i]) / (h * 6.0);
×
848

849
  return y[i] + b * r + c * r * r + d * r * r * r;
×
850
}
851

852
double spline_integrate(int n, const double x[], const double y[],
19,731,104 ✔
853
  const double z[], double xa, double xb)
854
{
855
  // Find the lower bounding index in x of the lower limit of integration.
856
  int ia = n - 1;
19,731,104 ✔
857
  while (--ia) {
1,320,604,202 ✔
858
    if (xa >= x[ia])
1,320,407,642 ✔
859
      break;
860
  }
861

862
  // Find the lower bounding index in x of the upper limit of integration.
863
  int ib = n - 1;
864
  while (--ib) {
1,301,069,658 !
865
    if (xb >= x[ib])
1,301,069,658 ✔
866
      break;
867
  }
868

869
  // Evaluate the integral
870
  double s = 0.0;
871
  for (int i = ia; i <= ib; i++) {
58,996,752 ✔
872
    double h = x[i + 1] - x[i];
39,265,648 ✔
873

874
    // Compute the coefficients
875
    double b = (y[i + 1] - y[i]) / h - (h / 6.0) * (z[i + 1] + 2.0 * z[i]);
39,265,648 ✔
876
    double c = z[i] / 2.0;
39,265,648 ✔
877
    double d = (z[i + 1] - z[i]) / (h * 6.0);
39,265,648 ✔
878

879
    // Subtract the integral from x[ia] to xa
880
    if (i == ia) {
39,265,648 ✔
881
      double r = xa - x[ia];
19,731,104 ✔
882
      s = s - (y[i] * r + b / 2.0 * r * r + c / 3.0 * r * r * r +
19,731,104 ✔
883
                d / 4.0 * r * r * r * r);
19,731,104 ✔
884
    }
885

886
    // Integrate from x[ib] to xb in final interval
887
    if (i == ib) {
39,265,648 ✔
888
      h = xb - x[ib];
19,731,104 ✔
889
    }
890

891
    // Accumulate the integral
892
    s = s + y[i] * h + b / 2.0 * h * h + c / 3.0 * h * h * h +
39,265,648 ✔
893
        d / 4.0 * h * h * h * h;
39,265,648 ✔
894
  }
895

896
  return s;
19,731,104 ✔
897
}
898

899
std::complex<double> faddeeva(std::complex<double> z)
254,391,841 ✔
900
{
901
  // Technically, the value we want is given by the equation:
902
  // w(z) = I/pi * Integrate[Exp[-t^2]/(z-t), {t, -Infinity, Infinity}]
903
  // as shown in Equation 63 from Hwang, R. N. "A rigorous pole
904
  // representation of multilevel cross sections and its practical
905
  // applications." Nucl. Sci. Eng. 96.3 (1987): 192-209.
906
  //
907
  // The MIT Faddeeva function evaluates w(z) = exp(-z^2)erfc(-iz). These
908
  // two forms of the Faddeeva function are related by a transformation.
909
  //
910
  // If we call the integral form w_int, and the function form w_fun:
911
  // For imag(z) > 0, w_int(z) = w_fun(z)
912
  // For imag(z) < 0, w_int(z) = -conjg(w_fun(conjg(z)))
913

914
  // Note that Faddeeva::w will interpret zero as machine epsilon
915
  return z.imag() > 0.0 ? Faddeeva::w(z)
254,391,841 !
916
                        : -std::conj(Faddeeva::w(std::conj(z)));
254,391,841 !
917
}
918

919
std::complex<double> w_derivative(std::complex<double> z, int order)
4,232,547 ✔
920
{
921
  using namespace std::complex_literals;
4,232,547 ✔
922
  switch (order) {
4,232,547 ✔
923
  case 0:
1,410,849 ✔
924
    return faddeeva(z);
1,410,849 ✔
925
  case 1:
1,410,849 ✔
926
    return -2.0 * z * faddeeva(z) + 2.0i / SQRT_PI;
1,410,849 ✔
927
  default:
1,410,849 ✔
928
    return -2.0 * z * w_derivative(z, order - 1) -
1,410,849 ✔
929
           2.0 * (order - 1) * w_derivative(z, order - 2);
1,410,849 ✔
930
  }
931
}
932

UNCOV
933
double exprel(double x)
×
934
{
935
  if (std::abs(x) < 1e-16)
×
936
    return 1.0;
937
  else {
UNCOV
938
    return std::expm1(x) / x;
×
939
  }
940
}
941

UNCOV
942
double log1prel(double x)
×
943
{
944
  if (std::abs(x) < 1e-16)
×
945
    return 1.0;
946
  else {
UNCOV
947
    return std::log1p(x) / x;
×
948
  }
949
}
950

951
double cyl_bessel_j(int n, double x)
264 ✔
952
{
953
  // Handle negative arguments via the parity relation
954
  // J_n(-x) = (-1)^n J_n(x); std::cyl_bessel_j has a domain error for x < 0.
955
  double sign = 1.0;
264 ✔
956
  if (x < 0.0) {
264 ✔
957
    x = -x;
88 ✔
958
    if (n % 2 == 1)
88 ✔
959
      sign = -1.0;
44 ✔
960
  }
961

962
#if defined(__cpp_lib_math_special_functions) &&                               \
963
  __cpp_lib_math_special_functions >= 201603L
964
  return sign * std::cyl_bessel_j(static_cast<double>(n), x);
264 ✔
965
#else
966
  // Ascending power series (e.g., Abramowitz & Stegun eq. 9.1.10):
967
  //   J_n(x) = sum_{m=0}^inf (-1)^m / (m! (m+n)!) * (x/2)^(2m+n)
968
  // The term ratio is -(x/2)^2 / (m*(m+n)), so for |x| <= 2 the series
969
  // converges to machine precision within ~20 terms.
970
  double half_x = 0.5 * x;
971

972
  // First term: (x/2)^n / n!
973
  double term = 1.0;
974
  for (int k = 1; k <= n; ++k) {
975
    term *= half_x / k;
976
  }
977

978
  double sum = term;
979
  double neg_half_x_sq = -half_x * half_x;
980
  for (int m = 1; m <= 50; ++m) {
981
    term *= neg_half_x_sq / (m * (m + n));
982
    sum += term;
983
    if (std::abs(term) <=
984
        std::numeric_limits<double>::epsilon() * std::abs(sum))
985
      break;
986
  }
987
  return sign * sum;
988
#endif
989
}
990

991
// Helper function to get index and interpolation function on an incident energy
992
// grid
993
void get_energy_index(
1,652,593,314 ✔
994
  const vector<double>& energies, double E, int& i, double& f)
995
{
996
  // Get index and interpolation factor for linear-linear energy grid
997
  i = 0;
1,652,593,314 ✔
998
  f = 0.0;
1,652,593,314 ✔
999
  if (E >= energies.front()) {
1,652,593,314 ✔
1000
    i = lower_bound_index(energies.begin(), energies.end(), E);
1,652,591,860 ✔
1001
    if (i + 1 < energies.size())
1,652,591,860 ✔
1002
      f = (E - energies[i]) / (energies[i + 1] - energies[i]);
1,652,590,518 ✔
1003
  }
1004
}
1,652,593,314 ✔
1005

1006
// Return true if two floating-point values are approximately equal within a
1007
// combined relative and absolute tolerance.
1008
bool isclose(double a, double b, double rel_tol, double abs_tol)
2,147,483,647 ✔
1009
{
1010
  return std::abs(a - b) <=
2,147,483,647 ✔
1011
         std::max(rel_tol * std::max(std::abs(a), std::abs(b)), abs_tol);
2,147,483,647 ✔
1012
}
1013

1014
bool combine_estimates(const array<double, 3>& estimates,
11,166 ✔
1015
  const tensor::StaticTensor2D<double, 3, 3>& cov, int64_t n,
1016
  array<double, 2>& combined)
1017
{
1018
  combined[0] = 0.0;
11,166 ✔
1019
  combined[1] = 0.0;
11,166 ✔
1020

1021
  // The three-estimate expression has an n-3 term in a denominator, and the
1022
  // two-estimate expression an n-2 term
1023
  if (n <= 3)
11,166 ✔
1024
    return false;
1025

1026
  // Check to see if two estimates are the same. If they are, the three
1027
  // estimate expressions are singular and will produce floating-point
1028
  // exceptions, so an expression specifically derived for the combination of
1029
  // two estimates (vice three) is used instead.
1030

1031
  // First we will identify if there are any matching estimates
1032
  int i, j;
10,352 ✔
1033
  bool use_three = false;
10,352 ✔
1034
  if ((std::abs(estimates[0] - estimates[1]) / estimates[0] <
10,352 ✔
1035
        FP_REL_PRECISION) &&
10,352 ✔
1036
      (std::abs(cov(0, 0) - cov(1, 1)) / cov(0, 0) < FP_REL_PRECISION)) {
66 ✔
1037
    // 0 and 1 match, so only use 0 and 2 in our comparisons
1038
    i = 0;
1039
    j = 2;
1040

1041
  } else if ((std::abs(estimates[0] - estimates[2]) / estimates[0] <
10,297 ✔
1042
               FP_REL_PRECISION) &&
10,297 !
1043
             (std::abs(cov(0, 0) - cov(2, 2)) / cov(0, 0) < FP_REL_PRECISION)) {
11 !
1044
    // 0 and 2 match, so only use 0 and 1 in our comparisons
1045
    i = 0;
1046
    j = 1;
1047

1048
  } else if ((std::abs(estimates[1] - estimates[2]) / estimates[1] <
10,297 ✔
1049
               FP_REL_PRECISION) &&
10,297 !
1050
             (std::abs(cov(1, 1) - cov(2, 2)) / cov(1, 1) < FP_REL_PRECISION)) {
11 !
1051
    // 1 and 2 match, so only use 0 and 1 in our comparisons
1052
    i = 0;
1053
    j = 1;
1054

1055
  } else {
1056
    // No two estimates match, so set boolean to use all three estimates.
1057
    use_three = true;
10,297 ✔
1058
  }
1059

1060
  if (use_three) {
10,297 ✔
1061
    // Use three estimates as derived in the paper by Urbatsch
1062

1063
    // Initialize variables
1064
    double g = 0.0;
10,297 ✔
1065
    array<double, 3> S {};
10,297 ✔
1066

1067
    for (int l = 0; l < 3; ++l) {
41,188 ✔
1068
      // Permutations of the three estimates
1069
      int k;
30,891 ✔
1070
      switch (l) {
30,891 ✔
1071
      case 0:
1072
        i = 0;
1073
        j = 1;
1074
        k = 2;
1075
        break;
1076
      case 1:
10,297 ✔
1077
        i = 1;
10,297 ✔
1078
        j = 2;
10,297 ✔
1079
        k = 0;
10,297 ✔
1080
        break;
10,297 ✔
1081
      case 2:
10,297 ✔
1082
        i = 2;
10,297 ✔
1083
        j = 0;
10,297 ✔
1084
        k = 1;
10,297 ✔
1085
        break;
10,297 ✔
1086
      }
1087

1088
      // Calculate weighting
1089
      double f = cov(j, j) * (cov(k, k) - cov(i, k)) - cov(k, k) * cov(i, j) +
30,891 ✔
1090
                 cov(j, k) * (cov(i, j) + cov(i, k) - cov(j, k));
30,891 ✔
1091

1092
      // Add to S sums for variance of combined estimate
1093
      S[0] += f * cov(0, l);
30,891 ✔
1094
      S[1] +=
30,891 ✔
1095
        (cov(j, j) + cov(k, k) - 2.0 * cov(j, k)) * estimates[l] * estimates[l];
30,891 ✔
1096
      S[2] += (cov(k, k) + cov(i, j) - cov(j, k) - cov(i, k)) * estimates[l] *
30,891 ✔
1097
              estimates[j];
30,891 ✔
1098

1099
      // Add to sum for the combination
1100
      combined[0] += f * estimates[l];
30,891 ✔
1101
      g += f;
30,891 ✔
1102
    }
1103

1104
    // Complete calculations of S sums
1105
    for (auto& S_i : S) {
41,188 ✔
1106
      S_i *= (n - 1);
30,891 ✔
1107
    }
1108
    S[0] *= (n - 1) * (n - 1);
10,297 ✔
1109

1110
    // Calculate the combination
1111
    combined[0] /= g;
10,297 ✔
1112

1113
    // Calculate standard deviation of the combination
1114
    g *= (n - 1) * (n - 1);
10,297 ✔
1115
    combined[1] =
10,297 ✔
1116
      std::sqrt(S[0] / (g * n * (n - 3)) * (1 + n * ((S[1] - 2 * S[2]) / g)));
10,297 ✔
1117

1118
  } else {
1119
    // Use only two estimates
1120
    // These equations are derived analogously to that done in the paper by
1121
    // Urbatsch, but are simpler than for the three estimate case since the
1122
    // block matrices of the three estimate equations reduces to scalars here
1123

1124
    // Store the commonly used term
1125
    double f = estimates[i] - estimates[j];
55 ✔
1126
    double g = cov(i, i) + cov(j, j) - 2.0 * cov(i, j);
55 ✔
1127

1128
    // Calculate the combination
1129
    combined[0] = estimates[i] - (cov(i, i) - cov(i, j)) / g * f;
55 ✔
1130

1131
    // Calculate standard deviation of the combination. Urbatsch's Eq. 40 is
1132
    // written in terms of the matrix S rather than the sample covariance
1133
    // Sigma = S / (n - 1). The factor cancels in the combination itself but
1134
    // not here, and omitting it understates the standard deviation by up to
1135
    // sqrt(n - 1).
1136
    combined[1] = (cov(i, i) * cov(j, j) - cov(i, j) * cov(i, j)) *
55 ✔
1137
                  ((n - 1) * g + n * f * f) / (n * (n - 2) * g * g);
55 ✔
1138
    combined[1] = std::sqrt(combined[1]);
55 ✔
1139
  }
1140

1141
  return true;
1142
}
1143

1144
} // namespace openmc
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