Stan Math Library  2.15.0
reverse mode automatic differentiation
check_3F2_converges.hpp
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1 #ifndef STAN_MATH_PRIM_SCAL_ERR_CHECK_3F2_CONVERGES_HPP
2 #define STAN_MATH_PRIM_SCAL_ERR_CHECK_3F2_CONVERGES_HPP
3 
7 #include <cmath>
8 #include <stdexcept>
9 #include <sstream>
10 #include <limits>
11 
12 namespace stan {
13  namespace math {
14 
39  template <typename T_a1, typename T_a2, typename T_a3, typename T_b1,
40  typename T_b2, typename T_z>
41  inline void check_3F2_converges(const char* function,
42  const T_a1& a1, const T_a2& a2, const T_a3& a3, const T_b1& b1,
43  const T_b2& b2, const T_z& z
44  ) {
45  using std::floor;
46  using std::fabs;
47 
48  check_not_nan("check_3F2_converges", "a1", a1);
49  check_not_nan("check_3F2_converges", "a2", a2);
50  check_not_nan("check_3F2_converges", "a3", a3);
51  check_not_nan("check_3F2_converges", "b1", b1);
52  check_not_nan("check_3F2_converges", "b2", b2);
53  check_not_nan("check_3F2_converges", "z", z);
54 
55  int num_terms = 0;
56  bool is_polynomial = false;
57 
58  if (is_nonpositive_integer(a1) && fabs(a1) >= num_terms) {
59  is_polynomial = true;
60  num_terms = floor(fabs(value_of_rec(a1)));
61  }
62  if (is_nonpositive_integer(a2) && fabs(a2) >= num_terms) {
63  is_polynomial = true;
64  num_terms = floor(fabs(value_of_rec(a2)));
65  }
66  if (is_nonpositive_integer(a3) && fabs(a3) >= num_terms) {
67  is_polynomial = true;
68  num_terms = floor(fabs(value_of_rec(a3)));
69  }
70 
71  bool is_undefined = (is_nonpositive_integer(b1) &&
72  fabs(b1) <= num_terms) || (is_nonpositive_integer(b2) &&
73  fabs(b2) <= num_terms);
74 
75  if (is_polynomial && !is_undefined) return;
76  if (fabs(z) < 1.0 && !is_undefined) return;
77  if (fabs(z) == 1.0 && !is_undefined && b1 + b2 > a1 + a2 + a3) return;
78 
79  std::stringstream msg;
80  msg << "called from function '" << function << "', "
81  << "hypergeometric function 3F2 does not meet convergence "
82  << "conditions with given arguments. "
83  << "a1: " << a1 << ", a2: " << a2 << ", a3: " << a3
84  << ", b1: " << b1 << ", b2: " << b2 << ", z: " << z;
85  throw std::domain_error(msg.str());
86  }
87 
88  }
89 }
90 #endif
fvar< T > fabs(const fvar< T > &x)
Definition: fabs.hpp:15
void check_3F2_converges(const char *function, const T_a1 &a1, const T_a2 &a2, const T_a3 &a3, const T_b1 &b1, const T_b2 &b2, const T_z &z)
Check if the hypergeometric function (3F2) called with supplied arguments will converge, assuming arguments are finite values.
double value_of_rec(const fvar< T > &v)
Return the value of the specified variable.
bool is_nonpositive_integer(T x)
Returns true if the input is a nonpositive integer and false otherwise.
void check_not_nan(const char *function, const char *name, const T_y &y)
Check if y is not NaN.
void domain_error(const char *function, const char *name, const T &y, const char *msg1, const char *msg2)
Throw a domain error with a consistently formatted message.
fvar< T > floor(const fvar< T > &x)
Definition: floor.hpp:11

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