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BoysFunctionIntermediate Class Reference

Helper class for fast evaluations in BoysFunction. More...

#include <boysfunctionintermediate.h>

Public Member Functions

 BoysFunctionIntermediate (int levelMax=20, int nValues=1000, double limitMin=0.0, double limitMax=50.0, int nIntegralValues=1e7)
 
double result (double arg, int n) const
 
void updateResults ()
 

Static Public Member Functions

static BoysFunctionIntermediate & getInstance ()
 

Protected Member Functions

double integrand (double x, double t, double n) const
 
double directIntegral (double x, double n) const
 
double fastPow (double x, int a) const
 

Protected Attributes

const int m_taylorExpansionOrder = 6
 
double m_dx
 
double m_dxInverse
 
uint m_nValues
 
int m_levelMax
 
int m_neededLevelMax
 
double m_limitMin
 
double m_limitMax
 
uint m_nIntegralValues
 
mat m_results
 
vec m_args
 

Detailed Description

Helper class for fast evaluations in BoysFunction.

Definition at line 8 of file boysfunctionintermediate.h.

Constructor & Destructor Documentation

BoysFunctionIntermediate::BoysFunctionIntermediate ( int  levelMax = 20,
int  nValues = 1000,
double  limitMin = 0.0,
double  limitMax = 50.0,
int  nIntegralValues = 1e7 
)

Definition at line 13 of file boysfunctionintermediate.cpp.

13  :
14  m_nValues(nValues),
15  m_levelMax(levelMax),
16  m_neededLevelMax(m_levelMax + m_taylorExpansionOrder + 1),
17  m_limitMin(limitMin),
18  m_limitMax(limitMax),
19  m_nIntegralValues(nIntegralValues)
20 {
21  factorialInverseTable[0] = 1.0;
22  factorialInverseTable[1] = 1.0;
23  factorialInverseTable[2] = 0.5;
24  factorialInverseTable[3] = 0.166666666667;
25  factorialInverseTable[4] = 0.0416666666667;
26  factorialInverseTable[5] = 0.00833333333333;
27  factorialInverseTable[6] = 0.00138888888889;
28  factorialInverseTable[7] = 0.000198412698413;
29  factorialInverseTable[8] = 2.48015873016e-05;
30  factorialInverseTable[9] = 2.7557319224e-06;
31  factorialInverseTable[10] = 2.7557319224e-07;
32  factorialInverseTable[11] = 2.50521083854e-08;
33  factorialInverseTable[12] = 2.08767569879e-09;
34  factorialInverseTable[13] = 1.60590438368e-10;
35  factorialInverseTable[14] = 1.14707455977e-11;
36  factorialInverseTable[15] = 7.64716373182e-13;
37  factorialInverseTable[16] = 4.77947733239e-14;
38  factorialInverseTable[17] = 2.81145725435e-15;
39  factorialInverseTable[18] = 1.56192069686e-16;
40  factorialInverseTable[19] = 8.22063524662e-18;
41  factorialInverseTable[20] = 4.11031762331e-19;
42  factorialInverseTable[21] = 1.95729410634e-20;
43  factorialInverseTable[22] = 8.89679139245e-22;
44  factorialInverseTable[23] = 3.86817017063e-23;
45  factorialInverseTable[24] = 1.6117375711e-24;
46  factorialInverseTable[25] = 6.44695028438e-26;
47  factorialInverseTable[26] = 2.47959626322e-27;
48  factorialInverseTable[27] = 9.1836898638e-29;
49  factorialInverseTable[28] = 3.27988923707e-30;
50  factorialInverseTable[29] = 1.13099628864e-31;
51  factorialInverseTable[30] = 3.76998762882e-33;
52  factorialInverseTable[31] = 1.21612504155e-34;
53  factorialInverseTable[32] = 3.80039075485e-36;
54  factorialInverseTable[33] = 1.15163356208e-37;
55  factorialInverseTable[34] = 3.38715753552e-39;
56  factorialInverseTable[35] = 9.67759295863e-41;
57  factorialInverseTable[36] = 2.68822026629e-42;
58  factorialInverseTable[37] = 7.26546017915e-44;
59  factorialInverseTable[38] = 1.91196320504e-45;
60  factorialInverseTable[39] = 4.90246975651e-47;
61 
62  m_dx = (limitMax - limitMin) / (nValues - 1);
63  m_dxInverse = 1.0 / m_dx;
64  updateResults();
65 }

Member Function Documentation

double BoysFunctionIntermediate::directIntegral ( double  x,
double  n 
) const
protected

Definition at line 122 of file boysfunctionintermediate.cpp.

122  {
123  double t0 = 0.0;
124  double t1 = 1.0;
125  double nt = m_nIntegralValues;
126  double dt = (t1 - t0) / nt;
127  double integralResult = 0;
128  for(int i = 0; i < nt; i++) {
129  double t = t0 + dt * i;
130  integralResult += 2 * integrand(x, t + dt, n);
131  }
132  integralResult -= integrand(x, 0, n);
133  integralResult -= integrand(x, (nt - 1)*dt, n);
134  integralResult *= dt / 2.0;
135  return integralResult;
136 }
double BoysFunctionIntermediate::fastPow ( double  x,
int  a 
) const
protected

Definition at line 138 of file boysfunctionintermediate.cpp.

138  {
139  double powResult = 1;
140  for(int i = 0; i < a; i++) {
141  powResult *= x;
142  }
143  return powResult;
144 }
static BoysFunctionIntermediate& BoysFunctionIntermediate::getInstance ( )
inlinestatic

Definition at line 17 of file boysfunctionintermediate.h.

17  {
18  static BoysFunctionIntermediate instance;
19  return instance;
20  }
double BoysFunctionIntermediate::integrand ( double  x,
double  t,
double  n 
) const
protected

Definition at line 146 of file boysfunctionintermediate.cpp.

146  {
147  return exp(-x*t*t) * fastPow(t, 2*n);
148 }
double BoysFunctionIntermediate::result ( double  arg,
int  n 
) const

Definition at line 105 of file boysfunctionintermediate.cpp.

105  {
106  // Linear interpolation
107  double dx = m_dx;
108  double dxI = m_dxInverse;
109  int closestIndex = (arg - m_limitMin + dx * 0.5) * dxI; // + dx / 2.0 always gives the closest index
110  double closestArg = closestIndex * dx;
111  double difference = arg - closestArg;
112  double sumResult = m_results(closestIndex, n);
113  double powResult = 1;
114  for(int k = 1; k < m_taylorExpansionOrder + 1; k++) {
115  double F_n_k_x = m_results(closestIndex, n + k);
116  powResult *= -difference;
117  sumResult += F_n_k_x * powResult * factorialInverseTable[k];
118  }
119  return sumResult;
120 }
void BoysFunctionIntermediate::updateResults ( )

Definition at line 67 of file boysfunctionintermediate.cpp.

67  {
68  // Try to load results from file
69  stringstream fileNameStream;
70  fileNameStream << "boys_function_data"
71 // << "_lmax_" << m_levelMax
72  << "_nx" << m_nValues
73  << "_limmin_" << m_limitMin
74  << "_limmax_" << m_limitMax
75  << "_nt" << m_nIntegralValues
76  << ".arma";
77  bool allGood = m_results.load("boys_tabulated.dat");
78  if(!allGood) {
79  cout << "BoysFunctionIntermediate::updateResults(): Boys function data file not found. Generating now." << endl;
80  }
81  if(allGood) {
82  if(m_results.n_cols < uint(m_neededLevelMax)) {
83  cout << "BoysFunctionIntermediate::updateResults(): Boys function file has " << m_results.n_cols << " cols, "
84  << "but we need " << m_neededLevelMax << endl;
85  allGood = false;
86  }
87  }
88  if(!allGood) {
89  cout << "BoysFunctionIntermediate::updateResults(): Filename: " << fileNameStream.str() << endl;
90  cout << "BoysFunctionIntermediate::updateResults(): Max level: " << m_levelMax << endl;
91  m_results = zeros(m_nValues, m_neededLevelMax); // + 6 for the Taylor expansions
92  // Could not load results from file. Generate results and write file instead.
93  for(uint i = 0; i < m_nValues; i++) {
94  double x = i * m_dx;
95  cout << "x = " << x << endl;
96  for(uint n = 0; n < uint(m_neededLevelMax); n++) {
97  m_results(i,n) = directIntegral(x, n);
98  }
99  }
100  cout << "BoysFunctionIntermediate::updateResults(): Generating results done. Writing to file " << fileNameStream.str() << endl;
101  m_results.save(fileNameStream.str());
102  }
103 }

Member Data Documentation

vec BoysFunctionIntermediate::m_args
protected

Definition at line 35 of file boysfunctionintermediate.h.

double BoysFunctionIntermediate::m_dx
protected

Definition at line 24 of file boysfunctionintermediate.h.

double BoysFunctionIntermediate::m_dxInverse
protected

Definition at line 25 of file boysfunctionintermediate.h.

int BoysFunctionIntermediate::m_levelMax
protected

Definition at line 28 of file boysfunctionintermediate.h.

double BoysFunctionIntermediate::m_limitMax
protected

Definition at line 31 of file boysfunctionintermediate.h.

double BoysFunctionIntermediate::m_limitMin
protected

Definition at line 30 of file boysfunctionintermediate.h.

int BoysFunctionIntermediate::m_neededLevelMax
protected

Definition at line 29 of file boysfunctionintermediate.h.

uint BoysFunctionIntermediate::m_nIntegralValues
protected

Definition at line 32 of file boysfunctionintermediate.h.

uint BoysFunctionIntermediate::m_nValues
protected

Definition at line 27 of file boysfunctionintermediate.h.

mat BoysFunctionIntermediate::m_results
protected

Definition at line 34 of file boysfunctionintermediate.h.

const int BoysFunctionIntermediate::m_taylorExpansionOrder = 6
protected

Definition at line 23 of file boysfunctionintermediate.h.

The documentation for this class was generated from the following files:
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