diogo/yap-6.3
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support logsum, very useful in probability computatiion

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This commit is contained in:
Vitor Santos Costa 2013-07-25 10:20:33 -05:00
parent 1c2e17f86a
commit cc6e33bff0
2 changed files with 78 additions and 0 deletions
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69
C/eval.c
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@ -254,6 +254,74 @@ p_isinf( USES_REGS1 )
return isinf(FloatOfTerm(out));
}
static Int
p_logsum( USES_REGS1 )
{ /* X is Y */
Term t1 = Deref(ARG1);
Term t2 = Deref(ARG2);
int done = FALSE;
Float f1, f2;
while (!done) {
if (IsFloatTerm(t1)) {
f1 = FloatOfTerm(t1);
done = TRUE;
} else if (IsIntegerTerm(t1)) {
f1 = IntegerOfTerm(t1);
done = TRUE;
} else if (IsBigIntTerm(t1)) {
f1 = Yap_gmp_to_float(t1);
done = TRUE;
} else {
while (!(t1 = Eval(t1 PASS_REGS))) {
if (LOCAL_Error_TYPE == RESOURCE_ERROR_STACK) {
LOCAL_Error_TYPE = YAP_NO_ERROR;
if (!Yap_gcl(LOCAL_Error_Size, 1, ENV, CP)) {
Yap_Error(RESOURCE_ERROR_STACK, ARG2, LOCAL_ErrorMessage);
return FALSE;
}
} else {
Yap_Error(LOCAL_Error_TYPE, LOCAL_Error_Term, LOCAL_ErrorMessage);
return FALSE;
}
}
}
}
done = FALSE;
while (!done) {
if (IsFloatTerm(t2)) {
f2 = FloatOfTerm(t2);
done = TRUE;
} else if (IsIntegerTerm(t2)) {
f2 = IntegerOfTerm(t2);
done = TRUE;
} else if (IsBigIntTerm(t2)) {
f2 = Yap_gmp_to_float(t2);
done = TRUE;
} else {
while (!(t2 = Eval(t2 PASS_REGS))) {
if (LOCAL_Error_TYPE == RESOURCE_ERROR_STACK) {
LOCAL_Error_TYPE = YAP_NO_ERROR;
if (!Yap_gcl(LOCAL_Error_Size, 2, ENV, CP)) {
Yap_Error(RESOURCE_ERROR_STACK, ARG2, LOCAL_ErrorMessage);
return FALSE;
}
} else {
Yap_Error(LOCAL_Error_TYPE, LOCAL_Error_Term, LOCAL_ErrorMessage);
return FALSE;
}
}
}
}
if (f1 >= f2) {
Float fi = exp(f2-f1);
return Yap_unify(ARG3,MkFloatTerm(f1+log(1+fi)));
} else {
Float fi = exp(f1-f2);
return Yap_unify(ARG3,MkFloatTerm(f2+log(1+fi)));
}
}
Int
Yap_ArithError(yap_error_number type, Term where, char *format,...)
{
@ -418,6 +486,7 @@ Yap_InitEval(void)
Yap_InitCPred("is", 2, p_is, 0L);
Yap_InitCPred("isnan", 1, p_isnan, TestPredFlag);
Yap_InitCPred("isinf", 1, p_isinf, TestPredFlag);
Yap_InitCPred("logsum", 3, p_logsum, TestPredFlag);
Yap_InitCPredBack("between", 3, 2, init_between, cont_between, 0);
}

9
docs/yap.tex
View File

@ -4459,6 +4459,15 @@ The following predicates provide counting:
True if @var{Int3} = @var{Int1} + @var{Int2}. At least two of the
three arguments must be instantiated to integers.
@item logsum(+@var{Log1}, +@var{Log2}, -@var{Out} )
@findex logsum/3
@snindex logsum/3
@cnindex logsum/3
True if @var{Log1} is the logarithm of the positive number @var{A1},
@var{Log2} is the logarithm of the positive number @var{A2}, and
@var{Out} is the logarithm of the sum of the numbers @var{A1} and
@var{A2}. Useful in probability computation.
@item isnan(+@var{Float})
@findex isnan/1
@snindex isnan/1