Stan Math Library  2.20.0
reverse mode automatic differentiation
inv_square.hpp
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1 #ifndef STAN_MATH_FWD_SCAL_FUN_INV_SQUARE_HPP
2 #define STAN_MATH_FWD_SCAL_FUN_INV_SQUARE_HPP
3 
4 #include <stan/math/fwd/meta.hpp>
5 #include <stan/math/fwd/core.hpp>
7 
8 namespace stan {
9 namespace math {
10 
11 template <typename T>
12 inline fvar<T> inv_square(const fvar<T>& x) {
13  T square_x(square(x.val_));
14  return fvar<T>(1 / square_x, -2 * x.d_ / (square_x * x.val_));
15 }
16 } // namespace math
17 } // namespace stan
18 #endif
T d_
The tangent (derivative) of this variable.
Definition: fvar.hpp:50
fvar< T > square(const fvar< T > &x)
Definition: square.hpp:12
T val_
The value of this variable.
Definition: fvar.hpp:45
fvar< T > inv_square(const fvar< T > &x)
Definition: inv_square.hpp:12
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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