prob.3

这是一款很好用的工具包

Prob(3)                                                   Prob(3)



NNAAMMEE
       Prob - Probabilities for SRILM

SSYYNNOOPPSSIISS
       ##iinncclluuddee <<PPrroobb..hh>>

DDEESSCCRRIIPPTTIIOONN
       PPrroobb is a collection of types, constants and utility func-
       tions for handling probabilities in the SRILM library.

TTYYPPEESS
       PPrroobb   A floating point number representing a probability.

       LLooggPP   Logarithm to base 10 of a probability.

CCOONNSSTTAANNTTSS
       LLooggPP__ZZeerroo
              Log of probability 0.

       LLooggPP__IInnff
              Log  of probability infinity (not a legal probabil-
              ity, of course).

       LLooggPP__OOnnee
              Log of probability 1.

       LLooggPP__PPrreecciissiioonn
              The number of significant digits in a LogP

       PPrroobb__EEppssiilloonn
              A positive value close to 0; probability sums  less
              than this should be considered effectively zero.

FFUUNNCCTTIIOONNSS
       BBoooolleeaann ppaarrsseeLLooggPP((ccoonnsstt cchhaarr **_s_t_r_i_n_g,, LLooggPP &&_p_r_o_b))
              Converts  a  floating  point  string representation
              into a LogP.   Returns  ttrruuee  iff  the  number  was
              parsed  correctly.   This  function  should be much
              faster than generic C library functions for  float-
              ing point parsing.  Also, it parses singular LogP's
              (plus/minus infinity) correctly.

       PPrroobb LLooggPPttooPPPPLL((LLooggPP _p_r_o_b))
              Converts a LogP into a perplexity (PPL).

       PPrroobbTTooLLooggPP((PPrroobb prob))
              Converts a probability into a LogP.

       LLooggPP MMiixxLLooggPP((LLooggPP _p_r_o_b_1,, LLooggPP _p_r_o_b_2,, ddoouubbllee _l_a_m_b_d_a))
              Computes the LogP resulting from interpolating  two
              LogP's.  If _p_1 and _p_2 are probabilities correspond-
              ing to _p_r_o_b_1  and  _p_r_o_b_2,  respectively,  then  the
              result  is  the LogP corresponding to _l_a_m_b_d_a * _p_1 +
              (1 - _l_a_m_b_d_a) * _p_2.

       The following functions deal with _b_y_t_e_l_o_g_s.  Bytelogs  are
       logarithms  scaled  to  represent probabilties and likeli-
       hoods as a short integer in SRI's DECIPHER(TM)  recognizer
       (bytelog(_p) = log(_p) * 10000.5 / 1024).

       ddoouubbllee PPrroobbTTooBByytteelloogg((PPrroobb _p_r_o_b))
              Converts a probability to a bytelog.

       ddoouubbllee LLooggPPttooBByytteelloogg((LLooggPP _p_r_o_b))
              Convert a LogP to a bytelog.

       LLooggPP BByytteellooggTTooLLooggPP((ddoouubbllee _b_y_t_e_l_o_g))
              Convert a bytelog to a LogP.

SSEEEE AALLSSOO
BBUUGGSS
AAUUTTHHOORR
       Andreas Stolcke <[e-mail]>.
       Copyright 1995, 1996 SRI International



SRILM              $Date: 1996/07/13 01:35:40 $           Prob(3)