Stan Math Library  2.20.0
reverse mode automatic differentiation
square.hpp
Go to the documentation of this file.
1 #ifndef STAN_MATH_REV_SCAL_FUN_SQUARE_HPP
2 #define STAN_MATH_REV_SCAL_FUN_SQUARE_HPP
3 
4 #include <stan/math/rev/meta.hpp>
5 #include <stan/math/rev/core.hpp>
6 
7 namespace stan {
8 namespace math {
9 
10 namespace internal {
11 class square_vari : public op_v_vari {
12  public:
13  explicit square_vari(vari* avi) : op_v_vari(avi->val_ * avi->val_, avi) {}
14  void chain() { avi_->adj_ += adj_ * 2.0 * avi_->val_; }
15 };
16 } // namespace internal
17 
43 inline var square(const var& x) {
44  return var(new internal::square_vari(x.vi_));
45 }
46 
47 } // namespace math
48 } // namespace stan
49 #endif
The variable implementation base class.
Definition: vari.hpp:30
Independent (input) and dependent (output) variables for gradients.
Definition: var.hpp:33
void chain()
Apply the chain rule to this variable based on the variables on which it depends. ...
Definition: square.hpp:14
friend class var
Definition: vari.hpp:32
const double val_
The value of this variable.
Definition: vari.hpp:38
fvar< T > square(const fvar< T > &x)
Definition: square.hpp:12
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.