C++ parser for the zeros_nnnn.dat files

[Randall L. Rathbun]

For a C++ program which parses the dat files (any of the 14,580) which
are located in https://beta.lmfdb.org/riemann-zeta-zeros/data/ and gives
the zeta zero values (128 bits)

You are welcome to my program, the source is provided. I used 128 bit
mpf_class floating point accuracy on the calculations.

- Randall L. Rathbun


/* C++ Parser for zeros_nnnn.dat files
   NOTE: see https://beta.lmfdb.org/riemann-zeta-zeros/README.dvi
*/

#include <iostream>
#include <iomanip>
#include <sstream>
#include <fstream>
#include <gmpxx.h>

using namespace std;

int main( int argc, char *argv[] ) {

   streampos size;
   string file_name;

   union blockunion {
      char charblock[8];
      unsigned long blocks;
   } block_header;

   union tunion {
      char charblock[8];
      double dbl_t;
   } T0,T1;

   union nunion {
      char charblock[8];
      unsigned long ul_n;
   } N0,N1;

   struct zerostruct {
      unsigned long top;
      unsigned int mid;
      unsigned char bot;
   };

   union zerounion {
      char charblock[13];
      zerostruct zl;
   } zero_line;

   mpz_class ninty_six("79228162514264337593543950336");
   mpz_class sixty_four("18446744073709551616");
   mpf_class ozo("2535301200456458802993406410752.0",128);
   mpf_class one("1.0",128);
   mpf_class adj = one / ozo;

   if ( argc != 2 ) {
      cerr << "Command: parse_zeros zeros_nnn46000.dat" << endl << flush;
      return (-1);
   } else {
      file_name = argv[1];
   }

   ifstream infile;
   infile.open(file_name, ios::in|ios::binary);

   /* proceed with parsing if file open is successful */
   if (infile.is_open()) {

      /* B - number of blocks */
      infile.read(block_header.charblock,8);
      unsigned long blocks_in_file = block_header.blocks;
      cout << "---------------------------------------------------" <<
endl;
      cout << "-- Total blocks: " << blocks_in_file << " " << file_name
<< endl;
      cout << "---------------------------------------------------" <<
endl;

      /* iterate through blocks */
      for ( unsigned long block = 1; block <= block_header.blocks;
block++ ) {

         cout << "-- Block " << block << endl;
         infile.read(T0.charblock,8);
         double t0 = T0.dbl_t;
         cout << "--   t0 = " << t0 << endl;
         mpf_class mt0(t0,128); // important t_0 value for the file
         infile.read(T1.charblock,8);
         double t1 = T1.dbl_t;
         cout << "--   t1 = " << t1 << endl;
         infile.read(N0.charblock,8);
         unsigned long n0 = N0.ul_n;
         cout << "--   n0 = " << n0 << endl;
         infile.read(N1.charblock,8);
         unsigned long n1 = N1.ul_n;
         cout << "--   n1 = " << n1 << endl;
         unsigned long count_of_zeros = n1 - n0;
         cout << "--   " << count_of_zeros << " in this block" << endl;
         cout <<
"-------------------------------------------------------------" << endl;

         mpz_class sum_of_zeros = 0;

         for (unsigned long zeros = 1; zeros <= count_of_zeros; zeros++) {
            // cout << "zero # " << zeros << endl;
            infile.read(zero_line.charblock,13);
            unsigned long t = zero_line.zl.top;
            mpz_class mt(t);
            unsigned int m = zero_line.zl.mid;
            mpz_class mm(m);
            unsigned char b = zero_line.zl.bot;
            mpz_class mb(b);
            mpz_class zero = ninty_six * mb + sixty_four * mm + mt;
            // cout << "  zero = " << zero << endl;
            sum_of_zeros += zero;
            mpf_class fsoz(sum_of_zeros,128);
            mpf_class true_zero = mt0 + fsoz * adj;
            cout << zeros << "\t" << "1/2 + " << setprecision(62) <<
true_zero << "*I" << endl;

         } // loop over zeroes
         cout <<
"-------------------------------------------------------------" << endl;

      } // loop over blocks

   }
   else cout << "Unable to open file" << endl;
   infile.close();

   return 0;
}
/* Requirements:
   compile line: g++ parse_zeros.cpp -Wall -O2 -o parse_zeros -lgmpxx -lgmp
   requires gmp v6.3.0 https://gmplib.org/ and gcc C++ compiler std:C11
*/