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.\"
.IX Title "KinoSearch::Search::Similarity 3"
.TH KinoSearch::Search::Similarity 3 "2008-01-14" "perl v5.8.8" "User Contributed Perl Documentation"
void
STORABLE_thaw(blank_obj, cloning, serialized)
    \s-1SV\s0 *blank_obj;
    \s-1SV\s0 *cloning;
    \s-1SV\s0 *serialized;
\&\s-1PPCODE:\s0
{
    Similarity *sim = \fIKino_Sim_new()\fR;
    \s-1SV\s0 *deep_obj = SvRV(blank_obj);
    sv_setiv(deep_obj, \s-1PTR2IV\s0(sim));
}
.PP
void
new(either_sv)
    \s-1SV\s0 *either_sv;
\&\s-1PREINIT:\s0
    char       *class;
    Similarity *sim;
\&\s-1PPCODE:\s0
    /* determine the class */
    class = sv_isobject(either_sv) 
        ? sv_reftype(either_sv, 0) 
        : SvPV_nolen(either_sv);
.PP
.Vb 5
\&    /* build object */
\&    sim = Kino_Sim_new();
\&    ST(0)   = sv_newmortal();
\&    sv_setref_pv(ST(0), class, (void*)sim);
\&    XSRETURN(1);
.Ve
.PP
Provide a normalization factor for a field based on the square-root of the
number of terms in it.
.PP
Return a score factor based on the frequency of a term in a given document.
The default implementation is sqrt(freq).  Other implementations typically
produce ascending scores with ascending freqs, since the more times a doc
matches, the more relevant it is likely to be.
.PP
_float_to_byte and _byte_to_float encode and decode between 32\-bit \s-1IEEE\s0
floating point numbers and a 5\-bit exponent, 3\-bit mantissa float.  The range
covered by the single-byte encoding is 7x10^9 to 2x10^\-9.  The accuracy is
about one significant decimal digit.
.PP
The norm_decoder caches the 256 possible byte => float pairs, obviating the
need to call decode_norm over and over for a scoring implementation that
knows how to use it.