rand.h

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// g2o - General Graph Optimization
// Copyright (C) 2011 R. Kuemmerle, G. Grisetti, W. Burgard
// 
// g2o is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published
// by the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// 
// g2o is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Lesser General Public License for more details.
// 
// You should have received a copy of the GNU Lesser General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

#ifndef RAND_HH
#define RAND_HH

#include <cstdlib>
#include <cmath>
#include <ctime>

namespace g2o {

  namespace tutorial {

    class Rand
    {
      public:
        static double gauss_rand(double mean, double sigma)
        {
          double x, y, r2;
          do {
            x = -1.0 + 2.0 * uniform_rand(0.0, 1.0);
            y = -1.0 + 2.0 * uniform_rand(0.0, 1.0);
            r2 = x * x + y * y;
          } while (r2 > 1.0 || r2 == 0.0);
          return mean + sigma * y * std::sqrt(-2.0 * log(r2) / r2);
        }

        static double uniform_rand(double lowerBndr, double upperBndr)
        {
          return lowerBndr + ((double) std::rand() / (RAND_MAX + 1.0)) * (upperBndr - lowerBndr);
        }

        static void seed_rand()
        {
          seed_rand(std::time(NULL));
        }

        static void seed_rand(unsigned int seed)
        {
          std::srand(seed);
        }
    };

  } // end namespace
} // end namespace

#endif