gprune_heu.c File Reference

Calculate probability of a set of Gaussian densities by Gaussian pruning: heuristic algorithm. More...

#include <sent/stddefs.h>
#include <sent/htk_hmm.h>
#include <sent/htk_param.h>
#include <sent/hmm.h>
#include <sent/gprune.h>
#include "globalvars.h"

Include dependency graph for gprune_heu.c:

Go to the source code of this file.

Functions
static void	init_backmax ()
static void	make_backmax ()
static LOGPROB	compute_g_heu_updating (HTK_HMM_Dens *binfo)
	Calculate probability with maximum value update.
static LOGPROB	compute_g_heu_pruning (HTK_HMM_Dens *binfo, LOGPROB thres)
	Calculate probability with pruning.
boolean	gprune_heu_init ()
void	gprune_heu (HTK_HMM_Dens **g, int gnum, int *last_id)
	Compute a set of Gaussians with heuristic pruning.
Variables
static LOGPROB *	backmax
	Backward sum of max for each dimension (inversed).
static int	backmax_num
	Length of above.
static boolean *	mixcalced
	Mark which Gaussian has been computed.

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Detailed Description

Calculate probability of a set of Gaussian densities by Gaussian pruning: heuristic algorithm.

Author:

Akinobu LEE

Date:

Thu Feb 17 05:44:52 2005

gprune_heu() is one of the functions to compute output probability of a set of Gaussian densities. This function does heuristic pruning, trying to compute only the best ones for faster computation. If a tied-mixture HMM model with GPRUNE_DEFAULT_HEURISTIC defined in Julius, or explicitly specified by "-gprune heuristic" option, this function will be used.

The effect of heuristic pruning is practically a middle of others.

gprune_heu() will be used by calling outprob_init() to set its pointer to the global variable compute_gaussset. Then it will be called from calc_tied_mix() or calc_mix().

Revision

1.1.1.1

Definition in file gprune_heu.c.

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Function Documentation

static void init_backmax (   )  [static]

Clear backmax information. Definition at line 116 of file gprune_heu.c. Referenced by gprune_heu().

static void make_backmax (   )  [static]

Build backmax information for each frame, by summing up current maximum values of each dimensions. Definition at line 136 of file gprune_heu.c. Referenced by gprune_heu().

static LOGPROB compute_g_heu_updating (  HTK_HMM_Dens *  binfo  )  [static]

Calculate probability with maximum value update. Calculate probability of a Gaussian toward OP_vec, while storing the maximum values of each dimension to backmax. for future pruning. The pruning itself is not performed here. This function will be used to compute the first N Gaussians. Parameters: binfo  [in] Gaussian density Returns: the output log probability. Definition at line 162 of file gprune_heu.c. Referenced by gprune_heu().

static LOGPROB compute_g_heu_pruning (  HTK_HMM_Dens *  binfo, LOGPROB  thres )  [static]

Calculate probability with pruning. Calculate probability of a Gaussian toward OP_vec, performing pruning using threshold and the backmax information that has been set by compute_g_heu_updating() and make_backmax(). Parameters: binfo  [in] Gaussian density thres  [in] threshold Returns: the output log probability. Definition at line 200 of file gprune_heu.c. Referenced by gprune_heu().

boolean gprune_heu_init (   )

Initialize and setup work area for Gaussian pruning by heuristic algorithm. Returns: TRUE on success, FALSE on failure. Definition at line 235 of file gprune_heu.c. Referenced by outprob_init().

void gprune_heu (  HTK_HMM_Dens **  g, int  gnum, int *  last_id )

Compute a set of Gaussians with heuristic pruning. If the N-best mixtures in the previous frame is specified in last_id, They are first computed to get the maximum value for each dimension. After that, the rest of the Gaussians will be computed using the maximum values as heuristics of uncomputed dimensions to drop unpromising Gaussians from computation at early stage of likelihood computation. If the last_id is not specified (typically at the first frame of the input), a safe pruning as same as one in gprune_safe.c will be applied. The calculated scores will be stored to OP_calced_score, with its corresponding mixture id to OP_calced_id. These are done by calling cache_push(). The number of calculated mixtures is also stored in OP_calced_num. This can be called from calc_tied_mix() or calc_mix(). Parameters: g  [in] set of Gaussian densities to compute the output probability gnum  [in] length of above last_id  [in] ID list of N-best mixture in previous input frame, or NULL if not exist Definition at line 275 of file gprune_heu.c. Referenced by outprob_init().

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