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don't assert when suming numbers with negative infinity

This commit is contained in:
Tiago Gomes 2012-04-13 23:12:12 +01:00
parent 24a5fe9c23
commit f6e3bb4481
1 changed files with 23 additions and 14 deletions
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37
packages/CLPBN/clpbn/bp/Util.h
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@ -153,30 +153,39 @@ std::ostream& operator << (std::ostream& os, const vector<T>& v)
namespace {
const double INF = -numeric_limits<double>::infinity();
const double NEG_INF = -numeric_limits<double>::infinity();
};
inline double
Util::logSum (double x, double y)
{
return log (exp (x) + exp (y));
assert (isfinite (x) && isfinite (y));
// If one value is much smaller than the other, keep the larger value.
if (x < (y - log (1e200))) {
// std::log (std::exp (x) + std::exp (y)) can overflow!
assert (std::isnan (x) == false);
assert (std::isnan (y) == false);
if (x == NEG_INF) {
return y;
}
if (y < (x - log (1e200))) {
if (y == NEG_INF) {
return x;
}
double diff = x - y;
assert (isfinite (diff) && isfinite (x) && isfinite (y));
if (!isfinite (exp (diff))) {
// if one value is much smaller than the other,
// keep the larger value
const double tol = 460.517; // log (1e200)
if (x < y - tol) {
return y;
}
if (y < x - tol) {
return x;
}
assert (std::isnan (x - y) == false);
const double exp_diff = std::exp (x - y);
if (std::isfinite (exp_diff) == false) {
// difference is too large
return x > y ? x : y;
}
// otherwise return the sum.
return y + log (static_cast<double>(1.0) + exp (diff));
// otherwise return the sum
return y + std::log (static_cast<double>(1.0) + exp_diff);
}
@ -252,14 +261,14 @@ one()
inline double
zero() {
return Globals::logDomain ? INF : 0.0 ;
return Globals::logDomain ? NEG_INF : 0.0 ;
}
inline double
addIdenty()
{
return Globals::logDomain ? INF : 0.0;
return Globals::logDomain ? NEG_INF : 0.0;
}
@ -279,7 +288,7 @@ withEvidence()
inline double
noEvidence() {
return Globals::logDomain ? INF : 0.0;
return Globals::logDomain ? NEG_INF : 0.0;
}