Stan Math Library  2.20.0
reverse mode automatic differentiation
log2.hpp
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1 #ifndef STAN_MATH_FWD_SCAL_FUN_LOG2_HPP
2 #define STAN_MATH_FWD_SCAL_FUN_LOG2_HPP
3 
4 #include <stan/math/fwd/meta.hpp>
5 #include <stan/math/fwd/core.hpp>
8 
9 namespace stan {
10 namespace math {
11 
19 template <typename T>
20 inline fvar<T> log2(const fvar<T>& x) {
21  if (x.val_ < 0.0)
23  else
24  return fvar<T>(log2(x.val_), x.d_ / (x.val_ * LOG_2));
25 }
26 
27 } // namespace math
28 } // namespace stan
29 #endif
const double LOG_2
The natural logarithm of 2, .
Definition: constants.hpp:37
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
T val_
The value of this variable.
Definition: fvar.hpp:45
fvar< T > log2(const fvar< T > &x)
Return the base two logarithm of the specified argument.
Definition: log2.hpp:20
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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