Stan Math Library  2.20.0
reverse mode automatic differentiation
log.hpp
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1 #ifndef STAN_MATH_FWD_SCAL_FUN_LOG_HPP
2 #define STAN_MATH_FWD_SCAL_FUN_LOG_HPP
3 
4 #include <stan/math/fwd/meta.hpp>
5 #include <stan/math/fwd/core.hpp>
7 
8 namespace stan {
9 namespace math {
10 
11 template <typename T>
12 inline fvar<T> log(const fvar<T>& x) {
13  using std::log;
14  if (x.val_ < 0.0)
16  else
17  return fvar<T>(log(x.val_), x.d_ / x.val_);
18 }
19 } // namespace math
20 } // namespace stan
21 #endif
T d_
The tangent (derivative) of this variable.
Definition: fvar.hpp:50
const double NOT_A_NUMBER
(Quiet) not-a-number value.
Definition: constants.hpp:58
fvar< T > log(const fvar< T > &x)
Definition: log.hpp:12
T val_
The value of this variable.
Definition: fvar.hpp:45
var log(const var &a)
Return the natural log of the specified variable (cmath).
Definition: log.hpp:47
This template class represents scalars used in forward-mode automatic differentiation, which consist of values and directional derivatives of the specified template type.
Definition: fvar.hpp:41

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