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log_sum_exp.hpp
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1 #ifndef STAN_MATH_FWD_SCAL_FUN_LOG_SUM_EXP_HPP
2 #define STAN_MATH_FWD_SCAL_FUN_LOG_SUM_EXP_HPP
3
4 #include <stan/math/fwd/core.hpp>
5
6 #include <stan/math/prim/scal/fun/log_sum_exp.hpp>
7
8 namespace stan {
9
10 namespace math {
11
12 template <typename T>
13 inline
14 fvar<T>
15 log_sum_exp(const fvar<T>& x1, const fvar<T>& x2) {
16 using stan::math::log_sum_exp;
17 using std::exp;
18 return fvar<T>(log_sum_exp(x1.val_, x2.val_),
19 x1.d_ / (1 + exp(x2.val_ - x1.val_))
20 + x2.d_ / (exp(x1.val_ - x2.val_) + 1));
21 }
22
23 template <typename T>
24 inline
25 fvar<T>
26 log_sum_exp(const double x1, const fvar<T>& x2) {
27 using stan::math::log_sum_exp;
28 using std::exp;
29 return fvar<T>(log_sum_exp(x1, x2.val_),
30 x2.d_ / (exp(x1 - x2.val_) + 1));
31 }
32
33 template <typename T>
34 inline
35 fvar<T>
36 log_sum_exp(const fvar<T>& x1, const double x2) {
37 using stan::math::log_sum_exp;
38 using std::exp;
39 return fvar<T>(log_sum_exp(x1.val_, x2),
40 x1.d_ / (1 + exp(x2 - x1.val_)));
41 }
42
43 }
44 }
45 #endif
core.hpp
stan::math::fvar::d_
T d_
Definition: fvar.hpp:15
stan::math::log_sum_exp
fvar< T > log_sum_exp(const std::vector< fvar< T > > &v)
Definition: log_sum_exp.hpp:14
log_sum_exp.hpp
stan::math::fvar::val_
T val_
Definition: fvar.hpp:14
stan::math::exp
fvar< T > exp(const fvar< T > &x)
Definition: exp.hpp:10
stan::math::fvar
Definition: fvar.hpp:13

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