Stan Math Library  2.9.0
reverse mode automatic differentiation
Phi.hpp
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1 #ifndef STAN_MATH_REV_SCAL_FUN_PHI_HPP
2 #define STAN_MATH_REV_SCAL_FUN_PHI_HPP
3 
4 #include <stan/math/rev/core.hpp>
6 
7 namespace stan {
8  namespace math {
9 
10  namespace {
11  class Phi_vari : public op_v_vari {
12  public:
13  explicit Phi_vari(vari* avi) :
14  op_v_vari(stan::math::Phi(avi->val_), avi) {
15  }
16  void chain() {
17  static const double NEG_HALF = -0.5;
18  avi_->adj_ += adj_
20  * std::exp(NEG_HALF * avi_->val_ * avi_->val_);
21  }
22  };
23  }
24 
66  inline var Phi(const stan::math::var& a) {
67  return var(new Phi_vari(a.vi_));
68  }
69 
70  }
71 }
72 #endif
const double INV_SQRT_TWO_PI
Definition: constants.hpp:166
Independent (input) and dependent (output) variables for gradients.
Definition: var.hpp:31
fvar< T > exp(const fvar< T > &x)
Definition: exp.hpp:10
vari * vi_
Pointer to the implementation of this variable.
Definition: var.hpp:43
fvar< T > Phi(const fvar< T > &x)
Definition: Phi.hpp:14

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