Pierre8rTeam
80 lines
3.2 KiB
Plaintext
80 lines
3.2 KiB
Plaintext
//+------------------------------------------------------------------+
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//| PrimeGenerator.mqh |
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//| Copyright 2016, MetaQuotes Software Corp. |
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//| https://www.mql5.com |
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//+------------------------------------------------------------------+
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//+------------------------------------------------------------------+
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//| Class CPrimeGenrator. |
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//| Usage: Used to generate prime numbers. |
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//+------------------------------------------------------------------+
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class CPrimeGenerator
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{
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private:
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const static int s_primes[]; // table of prime numbers
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const static int s_hash_prime;
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public:
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static bool IsPrime(const int candidate);
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static int GetPrime(const int min);
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static int ExpandPrime(const int old_size);
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};
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const static int CPrimeGenerator::s_primes[]=
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{
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3,7,11,17,23,29,37,47,59,71,89,107,131,163,197,239,293,353,431,521,631,761,919,
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1103,1327,1597,1931,2333,2801,3371,4049,4861,5839,7013,8419,10103,12143,14591,
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17519,21023,25229,30293,36353,43627,52361,62851,75431,90523,108631,130363,156437,
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187751,225307,270371,324449,389357,467237,560689,672827,807403,968897,1162687,1395263,
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1674319,2009191,2411033,2893249,3471899,4166287,4999559,5999471,7199369
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};
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const static int CPrimeGenerator::s_hash_prime=101;
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//+------------------------------------------------------------------+
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//| Determines whether a value is prime. |
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//+------------------------------------------------------------------+
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bool CPrimeGenerator::IsPrime(const int candidate)
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{
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if((candidate &1)!=0)
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{
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int limit=(int)MathSqrt(candidate);
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//--- check value is prime
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for(int divisor=3; divisor<=limit; divisor+=2)
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if((candidate%divisor)==0)
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return(false);
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return(true);
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}
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return(candidate == 2);
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}
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//+------------------------------------------------------------------+
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//| Fast generator of parime value. |
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//+------------------------------------------------------------------+
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int CPrimeGenerator::GetPrime(const int min)
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{
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//--- a typical resize algorithm would pick the smallest prime number in this array
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//--- that is larger than twice the previous capacity.
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//--- get next prime value from table
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for(int i=0; i<ArraySize(s_primes); i++)
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{
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int prime=s_primes[i];
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if(prime>=min)
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return(prime);
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}
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//--- outside of our predefined table
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for(int i=(min|1); i<=INT_MAX;i+=2)
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{
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if(IsPrime(i) && ((i-1)%s_hash_prime!=0))
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return(i);
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}
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return(min);
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}
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//+------------------------------------------------------------------+
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//| Generate a new prime value greater than old_size. |
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//+------------------------------------------------------------------+
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int CPrimeGenerator::ExpandPrime(const int old_size)
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{
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int new_size=2*old_size;
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if((uint)new_size>INT_MAX && INT_MAX>old_size)
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return INT_MAX;
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else
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return GetPrime(new_size);
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}
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//+------------------------------------------------------------------+
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