Stan Math Library  2.12.0
reverse mode automatic differentiation
log1m_exp.hpp
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1 #ifndef STAN_MATH_FWD_SCAL_FUN_LOG1M_EXP_HPP
2 #define STAN_MATH_FWD_SCAL_FUN_LOG1M_EXP_HPP
3 
4 #include <stan/math/fwd/core.hpp>
8 #include <cmath>
9 
10 namespace stan {
11  namespace math {
12 
13  template <typename T>
14  inline
15  fvar<T>
16  log1m_exp(const fvar<T>& x) {
18  if (x.val_ >= 0)
19  return fvar<T>(NOT_A_NUMBER);
20  return fvar<T>(log1m_exp(x.val_), x.d_ / -expm1(-x.val_));
21  }
22 
23  }
24 }
25 #endif
const double NOT_A_NUMBER
(Quiet) not-a-number value.
Definition: constants.hpp:55
fvar< T > expm1(const fvar< T > &x)
Definition: expm1.hpp:12
fvar< T > log1m_exp(const fvar< T > &x)
Definition: log1m_exp.hpp:16

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