Stan Math Library  2.15.0
reverse mode automatic differentiation
operator_unary_negative.hpp
Go to the documentation of this file.
1 #ifndef STAN_MATH_REV_CORE_OPERATOR_UNARY_NEGATIVE_HPP
2 #define STAN_MATH_REV_CORE_OPERATOR_UNARY_NEGATIVE_HPP
3 
7 #include <limits>
8 
9 namespace stan {
10  namespace math {
11 
12  namespace {
13  class neg_vari : public op_v_vari {
14  public:
15  explicit neg_vari(vari* avi) :
16  op_v_vari(-(avi->val_), avi) {
17  }
18  void chain() {
19  if (unlikely(is_nan(avi_->val_)))
20  avi_->adj_ = std::numeric_limits<double>::quiet_NaN();
21  else
22  avi_->adj_ -= adj_;
23  }
24  };
25  }
26 
51  inline var operator-(const var& a) {
52  return var(new neg_vari(a.vi_));
53  }
54 
55  }
56 }
57 #endif
fvar< T > operator-(const fvar< T > &x1, const fvar< T > &x2)
Independent (input) and dependent (output) variables for gradients.
Definition: var.hpp:30
#define unlikely(x)
Definition: likely.hpp:9
vari * vi_
Pointer to the implementation of this variable.
Definition: var.hpp:42
int is_nan(const fvar< T > &x)
Returns 1 if the input&#39;s value is NaN and 0 otherwise.
Definition: is_nan.hpp:21

     [ Stan Home Page ] © 2011–2016, Stan Development Team.