Pi Compute Client for http://www.reddit.com/r/dailyprogrammer/comments/1qply1/111513_challenge_129_hard_baking_pi/

gistfile1.cpp

#include <cmath>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <limits>
#include <string>
#include <vector>

#include "Poco/Net/SocketAddress.h"
#include "Poco/Net/StreamSocket.h"

using namespace std;

double Series(unsigned int digit, int j) {
  double termsum = 0.0;
  for (int k = 0; k < digit; k++) {
    double numerator = pow(16.0, digit - k);
    double denominator = (8 * k + j);
    termsum += (numerator / denominator);
    termsum -= floor(termsum);
  }
  for (int k = digit; ; k++) {
    double numerator = 1.0;
    double denominator = (8 * k + j) * pow(16, k - digit);
    double fraction = numerator / denominator;
    if (fraction - 0.0  < 1e-32) break;
    termsum += (numerator / denominator);
    termsum -= floor(termsum);
  }
  return termsum;
}

double ComputePiDigit(unsigned int digit) {
  double value = (4 * Series(digit, 1) -
                  2 * Series(digit, 4) -
                  1 * Series(digit, 5) -
                  1 * Series(digit, 6));
  value = value - (unsigned long long) value + 1.0;
  return value;
}

// Special case for very first client connection: digitNum == -1
// Value has valid hex range, or else '1000'

struct PiState {
  int digitNum;
  unsigned int value;
};

int main(int argc, char **argv) {
  cout << "Connecting to " << argv[1] << ":" << argv[2] << endl;
  static const int kMaxDigits = 250;
  // Connect to the server, work with upto 10000 digits, then stop.
  Poco::Net::SocketAddress sa(argv[1], atoi(argv[2]));
  PiState my_pi_state;
  // First request is special
  my_pi_state.digitNum = -1;;
  my_pi_state.value = 1000;

  while (my_pi_state.digitNum < kMaxDigits) {

    Poco::Net::StreamSocket socket(sa);
    socket.setReceiveTimeout(100000);

    // contact server, give current result, get new digit to compute
    char bufstr[10];
    snprintf(bufstr, 10, "%d-%u", my_pi_state.digitNum, my_pi_state.value);
    socket.sendBytes(bufstr, 10);
    socket.receiveBytes(bufstr, 10);
    sscanf(bufstr, "*%d*", &my_pi_state.digitNum);
    double calculated_value = ComputePiDigit(my_pi_state.digitNum);
    // common case: compute the current digit and send it to the server

    cout << "Digit: " << dec << my_pi_state.digitNum << "...";
    float hexval = fabs(calculated_value);
    my_pi_state.value =
        static_cast<unsigned int>(16.0 * (hexval - floor(hexval)));
    cout << "Value: " << hex << my_pi_state.value << endl;

    // Anti-performance, but we want to work slowly here so I can start up
    // multiple clients and show their interleaved output :)
    sleep(1);
  }
  cout << "Pi Client exiting ..." << endl << endl;
}