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atanh.hpp
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#ifndef STAN_MATH_REV_SCAL_FUN_ATANH_HPP
#define STAN_MATH_REV_SCAL_FUN_ATANH_HPP
#include <math.h>
#include <stan/math/rev/core.hpp>
#include <cmath>
#include <limits>
namespace stan {
namespace math {
namespace {
class atanh_vari : public op_v_vari {
public:
atanh_vari(double val, vari* avi) :
op_v_vari(val, avi) {
}
void chain() {
avi_->adj_ += adj_ / (1.0 - avi_->val_ * avi_->val_);
}
};
}
inline var atanh(const var& a) {
if (a == 1.0)
return var(new atanh_vari(std::numeric_limits<double>::infinity(),
a.vi_));
if (a == -1.0)
return var(new atanh_vari(-std::numeric_limits<double>::infinity(),
a.vi_));
return var(new atanh_vari(::atanh(a.val()), a.vi_));
}
}
}
#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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