Stan Math Library  2.20.0
reverse mode automatic differentiation
cos.hpp
Go to the documentation of this file.
1 #ifndef STAN_MATH_REV_SCAL_FUN_COS_HPP
2 #define STAN_MATH_REV_SCAL_FUN_COS_HPP
3 
4 #include <stan/math/rev/meta.hpp>
5 #include <stan/math/rev/core.hpp>
6 #include <cmath>
7 
8 namespace stan {
9 namespace math {
10 
11 namespace internal {
12 class cos_vari : public op_v_vari {
13  public:
14  explicit cos_vari(vari* avi) : op_v_vari(std::cos(avi->val_), avi) {}
15  void chain() { avi_->adj_ -= adj_ * std::sin(avi_->val_); }
16 };
17 } // namespace internal
18 
46 inline var cos(const var& a) { return var(new internal::cos_vari(a.vi_)); }
47 
48 } // namespace math
49 } // namespace stan
50 #endif
fvar< T > cos(const fvar< T > &x)
Definition: cos.hpp:12
void chain()
Apply the chain rule to this variable based on the variables on which it depends. ...
Definition: cos.hpp:15
The variable implementation base class.
Definition: vari.hpp:30
Independent (input) and dependent (output) variables for gradients.
Definition: var.hpp:33
friend class var
Definition: vari.hpp:32
const double val_
The value of this variable.
Definition: vari.hpp:38
fvar< T > sin(const fvar< T > &x)
Definition: sin.hpp:11
vari * vi_
Pointer to the implementation of this variable.
Definition: var.hpp:45
double adj_
The adjoint of this variable, which is the partial derivative of this variable with respect to the ro...
Definition: vari.hpp:44

     [ Stan Home Page ] © 2011–2018, Stan Development Team.