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atanh.hpp
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1 #ifndef STAN_MATH_REV_SCAL_FUN_ATANH_HPP
2 #define STAN_MATH_REV_SCAL_FUN_ATANH_HPP
3
4 #include <math.h>
5 #include <stan/math/rev/core.hpp>
6 #include <cmath>
7 #include <limits>
8
9 namespace stan {
10 namespace math {
11
12 namespace {
13 class atanh_vari : public op_v_vari {
14 public:
15 atanh_vari(double val, vari* avi) :
16 op_v_vari(val, avi) {
17 }
18 void chain() {
19 avi_->adj_ += adj_ / (1.0 - avi_->val_ * avi_->val_);
20 }
21 };
22 }
23
65 inline var atanh(const var& a) {
66 if (a == 1.0)
67 return var(new atanh_vari(std::numeric_limits<double>::infinity(),
68 a.vi_));
69 if (a == -1.0)
70 return var(new atanh_vari(-std::numeric_limits<double>::infinity(),
71 a.vi_));
72 return var(new atanh_vari(::atanh(a.val()), a.vi_));
73 }
74
75 }
76 }
77 #endif
core.hpp
stan::math::atanh
fvar< T > atanh(const fvar< T > &x)
Definition: atanh.hpp:13
stan::math::var
Independent (input) and dependent (output) variables for gradients.
Definition: var.hpp:32
stan::math::var::vi_
vari * vi_
Pointer to the implementation of this variable.
Definition: var.hpp:44
stan::math::var::val
double val() const
Return the value of this variable.
Definition: var.hpp:234

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