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/*=============================================================================*\
* File: gfsmSemiring.def
* Author: Bryan Jurish <moocow@ling.uni-potsdam.de>
* Description: finite state machine library: semirings: inline definitions
*
* Copyright (c) 2004-2007 Bryan Jurish.
*
* 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
*=============================================================================*/
#include <float.h>
#include <math.h>
#include <string.h>
/*======================================================================
* Semiring: general utilities
*/
// LOG_BIG = log(1E31)
#define LOG_BIG 71.3801378828154
/*
//#define LOG_ZERO -FLT_MAX
#define LOG_ZERO -1E+38F
#define LOG_ONE 0
#define LOG_NONE 1
*/
GFSM_INLINE
gfsmWeight gfsm_log_add(gfsmWeight x, gfsmWeight y)
{
if (y-x > LOG_BIG) return y;
else if (x-y > LOG_BIG) return x;
/*else return min(x,y) + log(exp(x-min(x,y)) + exp(y-min(x,y))); */
else if (x<y) return x + log( 1 + exp(y-x));
else return y + log(exp(x-y) + 1);
}
#undef LOG_BIG
/*======================================================================
* Semiring: methods: constructors etc.
*/
/*--------------------------------------------------------------
* init()
*/
GFSM_INLINE
void gfsm_semiring_init(gfsmSemiring *sr, gfsmSRType type)
{
memset(sr, 0, type==gfsmSRTUser ? sizeof(gfsmUserSemiring) : sizeof(gfsmSemiring));
sr->type = type;
switch (type) {
case gfsmSRTBoolean:
sr->zero = 0;
sr->one = 1;
break;
case gfsmSRTLog:
sr->zero = FLT_MAX;
sr->one = 0;
break;
case gfsmSRTPLog:
sr->zero = -FLT_MAX;
sr->one = 0;
break;
case gfsmSRTTrivial:
sr->zero = 0;
sr->one = 0;
break;
case gfsmSRTTropical:
sr->zero = FLT_MAX;
sr->one = 0;
break;
case gfsmSRTReal:
default:
sr->zero = 0;
sr->one = 1;
break;
}
}
/*--------------------------------------------------------------
* new()
*/
GFSM_INLINE
gfsmSemiring *gfsm_semiring_new(gfsmSRType type)
{
gfsmSemiring *sr = (gfsmSemiring*)g_new(gfsmSemiring,1);
gfsm_semiring_init(sr,type);
return sr;
}
/*--------------------------------------------------------------
* user_new()
*/
GFSM_INLINE
gfsmUserSemiring *gfsm_user_semiring_new(gfsmSRBinaryPredicate equal_func,
gfsmSRBinaryPredicate less_func,
gfsmSRBinaryOp plus_func,
gfsmSRBinaryOp times_func)
{
gfsmUserSemiring *sr = g_new(gfsmUserSemiring, 1);
gfsm_semiring_init((gfsmSemiring*)sr,gfsmSRTUser);
sr->equal_func = equal_func;
sr->less_func = less_func;
sr->plus_func = plus_func;
sr->times_func = times_func;
return sr;
}
/*--------------------------------------------------------------
* copy()
*/
GFSM_INLINE
gfsmSemiring *gfsm_semiring_copy(gfsmSemiring *sr)
{
if (sr->type==gfsmSRTUser)
return (gfsmSemiring*)gfsm_user_semiring_new(((gfsmUserSemiring*)sr)->equal_func,
((gfsmUserSemiring*)sr)->less_func,
((gfsmUserSemiring*)sr)->plus_func,
((gfsmUserSemiring*)sr)->times_func);
return gfsm_semiring_new(sr->type);
}
/*--------------------------------------------------------------
* free()
*/
GFSM_INLINE
void gfsm_semiring_free(gfsmSemiring *sr)
{
if (sr->type==gfsmSRTUser) g_free((gfsmUserSemiring*)sr);
else g_free(sr);
}
/*======================================================================
* Semiring: methods: general accessors
*/
/*--------------------------------------------------------------
* zero()
*/
GFSM_INLINE
gfsmWeight gfsm_sr_zero(gfsmSemiring *sr) { return sr ? sr->zero : 0; }
/*--------------------------------------------------------------
* one()
*/
GFSM_INLINE
gfsmWeight gfsm_sr_one(gfsmSemiring *sr) { return sr ? sr->one : 1; }
/*--------------------------------------------------------------
* equal()
*/
GFSM_INLINE
gboolean gfsm_sr_equal(gfsmSemiring *sr, gfsmWeight x, gfsmWeight y)
{
return (sr->type == gfsmSRTUser && ((gfsmUserSemiring*)sr)->equal_func
? ((*((gfsmUserSemiring*)sr)->equal_func)(sr,x,y)) \
: (x==y));
}
/*--------------------------------------------------------------
* less()
*/
GFSM_INLINE
gboolean gfsm_sr_less(gfsmSemiring *sr, gfsmWeight x, gfsmWeight y)
{
switch (sr->type) {
case gfsmSRTLog:
case gfsmSRTTropical: return (x < y);
case gfsmSRTPLog: return (x > y);
case gfsmSRTTrivial: return 0;
case gfsmSRTUser:
if (((gfsmUserSemiring*)sr)->less_func)
return (*((gfsmUserSemiring*)sr)->less_func)(sr,x,y);
case gfsmSRTBoolean:
case gfsmSRTReal:
default: return (x > y);
}
return FALSE; //-- should never happen
}
/*--------------------------------------------------------------
* plus()
*/
GFSM_INLINE
gfsmWeight gfsm_sr_plus(gfsmSemiring *sr, gfsmWeight x, gfsmWeight y)
{
switch (sr->type) {
case gfsmSRTBoolean: return x || y;
//case gfsmSRTLog: return -log(exp(-x) + exp(-y));
case gfsmSRTLog: return -gfsm_log_add(-x,-y);
case gfsmSRTPLog: return gfsm_log_add( x, y);
case gfsmSRTTropical: return (x < y ? x : y);
case gfsmSRTTrivial: return 0;
case gfsmSRTUser:
if (((gfsmUserSemiring*)sr)->plus_func)
return (*((gfsmUserSemiring*)sr)->plus_func)(sr,x,y);
case gfsmSRTReal:
default: return x + y;
}
return sr->zero; //-- should never happen
}
/*--------------------------------------------------------------
* times()
*/
GFSM_INLINE
gfsmWeight gfsm_sr_times(gfsmSemiring *sr, gfsmWeight x, gfsmWeight y)
{
switch (sr->type) {
case gfsmSRTBoolean: return x && y;
case gfsmSRTLog:
case gfsmSRTPLog:
case gfsmSRTTropical: return x + y;
case gfsmSRTTrivial: return 0;
case gfsmSRTUser:
if (((gfsmUserSemiring*)sr)->times_func)
return (*((gfsmUserSemiring*)sr)->times_func)(sr,x,y);
case gfsmSRTReal:
default: return x * y;
}
return sr->zero; //-- should never happen
}
/*--------------------------------------------------------------
* div()
*/
/*gboolean gfsm_sr_div(gfsmSemiring *sr, gfsmWeight x, gfsmWeight y)
{ return (sr->div_func ? ((*sr->div_func)(sr,x,y)) : (x/y)); }
*/
//@}
/*======================================================================
* Semiring: string utilities
*/
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