class to generate prime numbers More...

Inheritance diagram for PrimeNumberSet< UIntType >:

Collaboration diagram for PrimeNumberSet< UIntType >:

Public Types
using	result_type = UIntType

Public Member Functions
	PrimeNumberSet ()
	default constructor More...

result_type	operator[] (size_t i) const

size_t	size () const

bool	get (UIntType offset, int n, std::vector< UIntType > &primes_add)
	add n new primes starting with an offset More...

Public Attributes
std::vector< UIntType >	primes

Detailed Description

template<typename UIntType>
struct PrimeNumberSet< UIntType >

class to generate prime numbers

Definition at line 55 of file PrimeNumberSet.h.

Member Typedef Documentation

◆ result_type

using result_type = UIntType

Definition at line 57 of file PrimeNumberSet.h.

Constructor & Destructor Documentation

◆ PrimeNumberSet()

PrimeNumberSet ( )

inline

default constructor

Reserve space for primes and construct min_prime-lowest prime numbers excluding 2

Definition at line 68 of file PrimeNumberSet.h.

   {
     primes.reserve(2 * min_num_primes);
     primes.push_back(3);
     result_type largest = 3;
     int n               = min_num_primes;
     while (n)
     {
       largest += 2;
       bool is_prime = true;
       for (int j = 0; j < primes.size(); j++)
       {
         if (largest % primes[j] == 0)
         {
           is_prime = false;
           break;
         }
         else if (primes[j] * primes[j] > largest)
         {
           break;
         }
       }
       if (is_prime)
       {
         primes.push_back(largest);
         n--;
       }
     }
   }

Member Function Documentation

◆ get()

bool get	(	UIntType	offset,
		int	n,
		std::vector< UIntType > &	primes_add
	)

inline

add n new primes starting with an offset

Parameters

offset	offset of a set
n	number of primes requested
primes_add	contains n prime numbers if successful

Returns: true, if successful

For i=[0,n), primes_add[i]=primes[offset+i]

Definition at line 110 of file PrimeNumberSet.h.

Referenced by RandomNumberControl::make_children(), RandomNumberControl::make_seeds(), RandomNumberControl::put(), and qmcplusplus::TEST_CASE().

   {
     offset = offset % max_prime_offset; //roll back
     //have enough prime numbers, assign them in an array
     if (n + offset + 1 < primes.size())
     {
       primes_add.insert(primes_add.end(), primes.begin() + offset, primes.begin() + offset + n);
       return true;
     }
     UIntType largest = primes.back();
     int n2add        = offset + n - primes.size();
     while (n2add > 0 && largest < max_prime)
     {
       largest += 2;
       bool is_prime = true;
       for (int j = 0; j < primes.size(); j++)
       {
         if (largest % primes[j] == 0)
         {
           is_prime = false;
           break;
         }
         else if (primes[j] * primes[j] > largest)
         {
           break;
         }
       }
       if (is_prime)
       {
         primes.push_back(largest);
         n2add--;
       }
     }
     if (n2add)
     {
       std::ostringstream o;
       o << "  PrimeNumberSet::get Failed to generate " << n2add << " prime numbers among " << n << " requested.";
       APP_ABORT(o.str());
       return false; //to make compiler happy
     }
     primes_add.insert(primes_add.end(), primes.begin() + offset, primes.begin() + offset + n);
     return true;
   }