OpenFPM_pdata  4.1.0 Project that contain the implementation of distributed structures
math_util_complex.hpp
1 /*
2  * math_util_complex.hpp
3  *
4  * Created on: Oct 1, 2017
5  * Author: i-bird
6  */
7
8 #ifndef OPENFPM_DATA_SRC_UTIL_MATH_UTIL_COMPLEX_HPP_
9 #define OPENFPM_DATA_SRC_UTIL_MATH_UTIL_COMPLEX_HPP_
10
12 extern std::vector<int> sieve_spf;
13
14 namespace openfpm
15 {
16  namespace math
17  {
18
19  #define SIEVE_MAXN 4096
20
26  void inline init_getFactorization()
27  {
28  sieve_spf.resize(SIEVE_MAXN);
29
30  sieve_spf[1] = 1;
31  for (int i = 2; i < SIEVE_MAXN; i++)
32  {
33  // marking smallest prime factor for every
34  // number to be itself.
35  sieve_spf[i] = i;
36  }
37
38  // separately marking spf for every even
39  // number as 2
40  for (int i = 4; i < SIEVE_MAXN; i += 2)
41  {sieve_spf[i] = 2;}
42
43  for (int i = 3; i*i < SIEVE_MAXN; i++)
44  {
45  // checking if i is prime
46  if (sieve_spf[i] == i)
47  {
48  // marking SPF for all numbers divisible by i
49  for (int j=i*i; j < SIEVE_MAXN; j+=i)
50  {
51  // marking spf[j] if it is not
52  // previously marked
53  if (sieve_spf[j] == j)
54  {sieve_spf[j] = i;}
55  }
56  }
57  }
58  }
59
67  inline void getFactorization(int x, std::vector<size_t> & ret)
68  {
69  ret.clear();
70  while (x != 1)
71  {
72  ret.push_back(sieve_spf[x]);
73  x = x / sieve_spf[x];
74  }
75  }
76
77  }
78 }
79
80
81 #endif /* OPENFPM_DATA_SRC_UTIL_MATH_UTIL_COMPLEX_HPP_ */
convert a type into constant type
Definition: aggregate.hpp:292