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#ifndef log_add_hh
#define log_add_hh
#include <limits>
#include <iostream>
#include <cassert>
#include <cmath>
template <typename T>
struct Log
{
static T zero() { return -std::numeric_limits<T>::infinity(); }
static T add(T l1, T l2)
{
if (l1 == zero()) return l2;
if (l1 > l2)
return l1 + std::log(1 + exp(l2 - l1));
else
return l2 + std::log(1 + exp(l1 - l2));
}
static T subtract(T l1, T l2)
{
//std::assert(l1 >= l2);
return l1 + log(1 - exp(l2 - l1));
}
};
#endif
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