diff options
Diffstat (limited to 'GIZA++-v2/logprob.cpp')
| -rw-r--r-- | GIZA++-v2/logprob.cpp | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/GIZA++-v2/logprob.cpp b/GIZA++-v2/logprob.cpp new file mode 100644 index 0000000..8134b77 --- /dev/null +++ b/GIZA++-v2/logprob.cpp @@ -0,0 +1,161 @@ +/* + +EGYPT Toolkit for Statistical Machine Translation +Written by Yaser Al-Onaizan, Jan Curin, Michael Jahr, Kevin Knight, John Lafferty, Dan Melamed, David Purdy, Franz Och, Noah Smith, and David Yarowsky. + +This program is free software; you can redistribute it and/or +modify it under the terms of the GNU General Public License +as published by the Free Software Foundation; either version 2 +of the License, or (at your option) any later version. + +This program 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 General Public License for more details. + +You should have received a copy of the GNU General Public License +along with this program; if not, write to the Free Software +Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, +USA. + +*/ +#pragma implementation + +// Routines to perform integer exponential arithmetic. +// A number x is represented as n, where x = b**n. +// It is assumed that b > 1, something like b = 1.001; + +#include "logprob.h" +#include <stdlib.h> +#include <stdio.h> +#include <iostream> +#include <fstream> +#include <string> +double *LogProb::ntof = NULL; // Tables will be initialized +int *LogProb::addtbl = NULL; // in Initialize function. +int *LogProb::subtbl = NULL; // + +const int LogProb::max_2byte_integer = 32767; +const int LogProb::min_2byte_integer = -32768; +const double LogProb::b = 1.001; // a logarithm basis +const double LogProb::logb2 = log(b); +//const int LogProb::nmax = round(78.0E0 * log(1.0E1) / logb2); +const int LogProb::nmax = round(300.0E0 * log(1.0E1) / logb2); +const int LogProb::nmin = -nmax; +const int LogProb::tblbnd = round(log((b-1.0E0)/2.0E0)/logb2); +const int LogProb::zeron = round(pow(-2, 23)); +const int LogProb::onen = 0; +const int LogProb::infn = onen - zeron; + +const int LogProb::initialized = LogProb::Initialize(); +const LogProb LogProb::zero(0); +const LogProb LogProb::one(1); +const LogProb LogProb::minus2(1e-2); +const LogProb LogProb::minus4(1e-4); +const LogProb LogProb::minus6(1e-6); +const LogProb LogProb::minus8(1e-8); +const LogProb LogProb::minus10(1e-10); +const LogProb LogProb::minus12(1e-12); +const LogProb LogProb::minus14(1e-14); +const LogProb LogProb::minus16(1e-16); + +// static table initialization function +int LogProb::Initialize() +{ + int nbytes = sizeof(double)*(nmax-nmin+1) + sizeof(int)*(0-tblbnd+1); + cerr << nbytes << " bytes used for LogProb tables (C++ version)\n"; + ntof = new double[nmax-nmin+1]; + addtbl = new int[-tblbnd+1]; + subtbl = new int[-tblbnd+1]; + + // char filename[257]; + // string filename ; + // ifstream ifs; + // ifs.open(filename.c_str()); + // if (!ifs) + // { + int i; + cerr << "Building integer logs conversion tables\n"; + ntof[0] = 0 ; + + for (i=nmin+1; i<=nmax; ++i) + { + double x = i; + ntof[i-nmin] = exp(x*logb2); + + } + for (i=tblbnd; i<=0; ++i) + { + double x = 1.0 + pow(b, i); + addtbl[i-tblbnd] = round(log(x)/logb2); + } + double sqrtb = exp(0.5*logb2); + for (i=0; i<=-tblbnd; ++i) + { + double x = sqrtb * pow(b, i) - 1.0; + subtbl[i] = round(log(x)/logb2); + } + // if (toolsRoot) + // { + // ofstream ofs(filename.c_str()); + // if (!ofs) + // cerr << "Could not write LogProb data to " << filename << endl; + // else + // { + // ofs.write((const char *)ntof, sizeof(double) * (nmax-nmin+1)); + // ofs.write((const char *)addtbl, sizeof(int) * (-tblbnd+1)); + // ofs.write((const char *)subtbl, sizeof(int) * (-tblbnd+1)); + // } + // } + // } + // else + // { + // ifs.read((char *)ntof, sizeof(double) * (nmax - nmin + 1)); + // ifs.read((char *)addtbl, sizeof(int) * (-tblbnd+1)); + // ifs.read((char *)subtbl, sizeof(int) * (-tblbnd+1)); + // } + return 1; +} + +void LogProb::FreeTables() +{ + delete [] addtbl; + delete [] subtbl; + delete [] ntof; +} + +//--------------------------------------------------------------------------- +// Aritmetic operators +//--------------------------------------------------------------------------- + + +// Subtract two logarithm numbers. Use the following method: +// b**n - b**m = b**m( b**(n-m) - 1 ), assuming n >= m. +LogProb& LogProb::operator-=(const LogProb &subs) +{ + if (subs.logr == zeron) + return *this; + int a = logr - subs.logr; + if (a <= 0) + { + if (a < 0) + { + cerr << "WARNING(logprob): Invalid arguments to nsub" <<(*this)<< " " << subs << endl; + //abort(); + } + logr = zeron; + return *this; + } + if (a > -tblbnd) + return *this; + logr = subs.logr + subtbl[a]; + return *this; +} + + + + + + + + |