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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>
6 #include <stan/math/prim/scal/fun/constants.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
stan::math::erf
var erf(const var &a)
The error function for variables (C99).
Definition: erf.hpp:68
core.hpp
stan
Definition: log_sum_exp.hpp:8
stan::math::erf
fvar< T > erf(const fvar< T > &x)
Definition: erf.hpp:14
stan::math::var
Independent (input) and dependent (output) variables for gradients.
Definition: var.hpp:31
stan::math::TWO_OVER_SQRT_PI
const double TWO_OVER_SQRT_PI
Definition: constants.hpp:161
stan::math::exp
fvar< T > exp(const fvar< T > &x)
Definition: exp.hpp:10
stan::math::var::vi_
vari * vi_
Pointer to the implementation of this variable.
Definition: var.hpp:43
constants.hpp

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