exponential_backoff.hpp

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#ifndef MLPACK_CORE_OPTIMIZERS_PARALLEL_SGD_EXP_BACKOFF_HPP
#define MLPACK_CORE_OPTIMIZERS_PARALLEL_SGD_EXP_BACKOFF_HPP

#include <mlpack/prereqs.hpp>

namespace mlpack {
namespace optimization {

class ExponentialBackoff
{
 public:
  ExponentialBackoff(const size_t firstBackoffEpoch,
                     const double step,
                     const double beta) :
    firstBackoffEpoch(firstBackoffEpoch),
    cutoffEpoch(firstBackoffEpoch),
    step(step),
    beta(beta)
  { /* Nothing to do. */ }

  double StepSize(const size_t numEpoch)
  {
    if (numEpoch >= cutoffEpoch)
    {
      step *= beta;
      cutoffEpoch += firstBackoffEpoch / beta;
    }
    return step;
  }

 private:
  size_t firstBackoffEpoch;

  size_t cutoffEpoch;

  double step;

  double beta;
};

} // namespace optimization
} // namespace mlpack

#endif