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multiply_log.hpp
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1 #ifndef STAN_MATH_REV_SCAL_FUN_MULTIPLY_LOG_HPP
2 #define STAN_MATH_REV_SCAL_FUN_MULTIPLY_LOG_HPP
3
4 #include <stan/math/rev/core.hpp>
5 #include <stan/math/rev/scal/fun/log.hpp>
6 #include <stan/math/prim/scal/fun/multiply_log.hpp>
7 #include <boost/math/special_functions/fpclassify.hpp>
8 #include <limits>
9
10 namespace stan {
11 namespace math {
12
13 namespace {
14 class multiply_log_vv_vari : public op_vv_vari {
15 public:
16 multiply_log_vv_vari(vari* avi, vari* bvi) :
17 op_vv_vari(stan::math::multiply_log(avi->val_, bvi->val_), avi, bvi) {
18 }
19 void chain() {
20 using std::log;
21 if (unlikely(boost::math::isnan(avi_->val_)
22 || boost::math::isnan(bvi_->val_))) {
23 avi_->adj_ = std::numeric_limits<double>::quiet_NaN();
24 bvi_->adj_ = std::numeric_limits<double>::quiet_NaN();
25 } else {
26 avi_->adj_ += adj_ * log(bvi_->val_);
27 if (bvi_->val_ == 0.0 && avi_->val_ == 0)
28 bvi_->adj_ += adj_ * std::numeric_limits<double>::infinity();
29 else
30 bvi_->adj_ += adj_ * avi_->val_ / bvi_->val_;
31 }
32 }
33 };
34 class multiply_log_vd_vari : public op_vd_vari {
35 public:
36 multiply_log_vd_vari(vari* avi, double b) :
37 op_vd_vari(stan::math::multiply_log(avi->val_, b), avi, b) {
38 }
39 void chain() {
40 using std::log;
41 if (unlikely(boost::math::isnan(avi_->val_)
42 || boost::math::isnan(bd_)))
43 avi_->adj_ = std::numeric_limits<double>::quiet_NaN();
44 else
45 avi_->adj_ += adj_ * log(bd_);
46 }
47 };
48 class multiply_log_dv_vari : public op_dv_vari {
49 public:
50 multiply_log_dv_vari(double a, vari* bvi) :
51 op_dv_vari(stan::math::multiply_log(a, bvi->val_), a, bvi) {
52 }
53 void chain() {
54 if (bvi_->val_ == 0.0 && ad_ == 0.0)
55 bvi_->adj_ += adj_ * std::numeric_limits<double>::infinity();
56 else
57 bvi_->adj_ += adj_ * ad_ / bvi_->val_;
58 }
59 };
60 }
61
74 inline var multiply_log(const var& a, const var& b) {
75 return var(new multiply_log_vv_vari(a.vi_, b.vi_));
76 }
87 inline var multiply_log(const var& a, const double b) {
88 return var(new multiply_log_vd_vari(a.vi_, b));
89 }
101 inline var multiply_log(const double a, const var& b) {
102 if (a == 1.0)
103 return log(b);
104 return var(new multiply_log_dv_vari(a, b.vi_));
105 }
106
107 }
108 }
109 #endif
core.hpp
stan
Definition: log_sum_exp.hpp:8
stan::math::log
fvar< T > log(const fvar< T > &x)
Definition: log.hpp:15
stan::math::var
Independent (input) and dependent (output) variables for gradients.
Definition: var.hpp:31
boost::math::isnan
bool isnan(const stan::math::var &v)
Checks if the given number is NaN.
Definition: boost_isnan.hpp:22
unlikely
#define unlikely(x)
Definition: likely.hpp:9
multiply_log.hpp
log.hpp
stan::math::var::vi_
vari * vi_
Pointer to the implementation of this variable.
Definition: var.hpp:43
stan::math::multiply_log
fvar< T > multiply_log(const fvar< T > &x1, const fvar< T > &x2)
Definition: multiply_log.hpp:15

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