lbfgs.h

Conditional Random Fields的训练识别工具

/*
  CRF++ -- Yet Another CRF toolkit

  $Id: lbfgs.h 1528 2006-08-07 02:39:50Z taku $;

  Copyright(C) 2005 Taku Kudo <[e-mail]>

  This is free software with ABSOLUTELY NO WARRANTY.

  This library 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 2.1 of the License, or(at your option) any later version.

  This library 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 library; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/
#ifndef MECAB_LBFGS_H
#define MECAB_LBFGS_H

#include <vector>
#include "common.h"

extern "C" {
  extern void lbfgs(int* n, int* m, double* x, double* f, double* g,
                    int* diagco, double* diag, int* iprint, double* eps,
                    double* xtol, double* w, int* iflag);
}

namespace CRFPP {

  class LBFGS {

  private:
    int n_;
    int m_;
    int iflag_;
    whatlog what_;
    std::vector <double> diag_;
    std::vector <double> w_;

  public:
    explicit LBFGS(): n_(0), m_(5), iflag_(0) {};
    virtual ~LBFGS() {};

    const char *what() { return what_.str(); }

    int init(int _n, int _m) {
      n_ = _n;
      m_ = _m;
      w_.resize(n_ *(2 * m_ + 1) + 2 * m_);
      diag_.resize(n_);
      return 0;
    }

    int optimize(double *x, double *f, double *g) {
      int iprint[] = {-1, 0};
      double eta  = 1e-7;
      double xtol = 1e-7;
      int diagco = 0;
      lbfgs(&n_, &m_, x, f, g, &diagco, &diag_[0], iprint, &eta, &xtol, &w_[0], &iflag_);

      if (iflag_ < 0) {
        CHECK_FALSE(false) << "routine stops with unexpected error";
        return -1;
      }

      if (iflag_ == 0) return 0; // terminate

      return 1; // evaluate next f and g
    }
  };
}

#endif