Stan Math Library  2.15.0
reverse mode automatic differentiation
log1p_exp.hpp
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1 #ifndef STAN_MATH_PRIM_SCAL_FUN_LOG1P_EXP_HPP
2 #define STAN_MATH_PRIM_SCAL_FUN_LOG1P_EXP_HPP
3 
5 #include <cmath>
6 
7 namespace stan {
8  namespace math {
9 
42  inline double log1p_exp(double a) {
43  using std::exp;
44  // like log_sum_exp below with b=0.0; prevents underflow
45  if (a > 0.0)
46  return a + log1p(exp(-a));
47  return log1p(exp(a));
48  }
49 
50  }
51 }
52 
53 #endif
fvar< T > exp(const fvar< T > &x)
Definition: exp.hpp:10
fvar< T > log1p_exp(const fvar< T > &x)
Definition: log1p_exp.hpp:13
fvar< T > log1p(const fvar< T > &x)
Definition: log1p.hpp:11

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