Stan Math Library  2.9.0
reverse mode automatic differentiation
erf.hpp
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1 #ifndef STAN_MATH_REV_SCAL_FUN_ERF_HPP
2 #define STAN_MATH_REV_SCAL_FUN_ERF_HPP
3 
4 #include <math.h>
5 #include <stan/math/rev/core.hpp>
7 #include <cmath>
8 #include <valarray>
9 
10 #ifdef _MSC_VER
11 #include <boost/math/special_functions/erf.hpp>
12 using boost::math::erf;
13 #endif
14 
15 namespace stan {
16  namespace math {
17 
18  namespace {
19  class erf_vari : public op_v_vari {
20  public:
21  explicit erf_vari(vari* avi) :
22  op_v_vari(::erf(avi->val_), avi) {
23  }
24  void chain() {
25  avi_->adj_ += adj_ * stan::math::TWO_OVER_SQRT_PI
26  * std::exp(- avi_->val_ * avi_->val_);
27  }
28  };
29  }
30 
68  inline var erf(const var& a) {
69  return var(new erf_vari(a.vi_));
70  }
71 
72  }
73 }
74 #endif
var erf(const var &a)
The error function for variables (C99).
Definition: erf.hpp:68
fvar< T > erf(const fvar< T > &x)
Definition: erf.hpp:14
Independent (input) and dependent (output) variables for gradients.
Definition: var.hpp:31
const double TWO_OVER_SQRT_PI
Definition: constants.hpp:161
fvar< T > exp(const fvar< T > &x)
Definition: exp.hpp:10
vari * vi_
Pointer to the implementation of this variable.
Definition: var.hpp:43

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