Stan Math Library  2.20.0
reverse mode automatic differentiation
sqrt.hpp
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1 #ifndef STAN_MATH_FWD_SCAL_FUN_SQRT_HPP
2 #define STAN_MATH_FWD_SCAL_FUN_SQRT_HPP
3 
4 #include <stan/math/fwd/meta.hpp>
5 #include <stan/math/fwd/core.hpp>
6 
8 
9 namespace stan {
10 namespace math {
11 
12 template <typename T>
13 inline fvar<T> sqrt(const fvar<T>& x) {
14  using std::sqrt;
15  return fvar<T>(sqrt(x.val_), 0.5 * x.d_ * inv_sqrt(x.val_));
16 }
17 } // namespace math
18 } // namespace stan
19 #endif
fvar< T > inv_sqrt(const fvar< T > &x)
Definition: inv_sqrt.hpp:11
T d_
The tangent (derivative) of this variable.
Definition: fvar.hpp:50
fvar< T > sqrt(const fvar< T > &x)
Definition: sqrt.hpp:13
var sqrt(const var &a)
Return the square root of the specified variable (cmath).
Definition: sqrt.hpp:47
T val_
The value of this variable.
Definition: fvar.hpp:45
This template class represents scalars used in forward-mode automatic differentiation, which consist of values and directional derivatives of the specified template type.
Definition: fvar.hpp:41

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