stan::math::var_value< T, require_floating_point_t< T > > Class Template Reference

Detailed Description

template<typename T>
class stan::math::var_value< T, require_floating_point_t< T > >

Independent (input) and dependent (output) variables for gradients.

This class acts as a smart pointer, with resources managed by an arena-based memory manager scoped to a single gradient calculation.

A var is constructed with a type T and used like any other scalar. Arithmetical functions like negation, addition, and subtraction, as well as a range of mathematical functions like exponentiation and powers are overridden to operate on var values objects.

Template Parameters

T	An Floating point type.

Definition at line 40 of file var.hpp.

#include <var.hpp>

Public Types
using	value_type = std::decay_t< T >
using	vari_type = vari_value< value_type >

Public Member Functions
bool	is_uninitialized ()
	Return true if this variable has been declared, but not been defined.
	var_value ()
	Construct a variable for later assignment.
template<typename S , require_convertible_t< S &, value_type > * = nullptr>
	var_value (S x)
	Construct a variable from the specified floating point argument by constructing a new vari_value<value_type>.
	var_value (vari_type *vi)
	Construct a variable from a pointer to a variable implementation.
const auto &	val () const noexcept
	Return a constant reference to the value of this variable.
auto &	adj () const noexcept
	Return a reference of the derivative of the root expression with respect to this expression.
auto &	adj () noexcept
	Return a reference to the derivative of the root expression with respect to this expression.
void	grad (std::vector< var_value< T > > &x, std::vector< value_type > &g)
	Compute the gradient of this (dependent) variable with respect to the specified vector of (independent) variables, assigning the specified vector to the gradient.
void	grad ()
	Compute the gradient of this (dependent) variable with respect to all (independent) variables.
vari_type &	operator* ()
	Return a reference to underlying implementation of this variable.
vari_type *	operator-> ()
	Return a pointer to the underlying implementation of this variable.
var_value< T > &	operator+= (const var_value< T > &b)
	The compound add/assignment operator for variables (C++).
var_value< T > &	operator+= (T b)
	The compound add/assignment operator for scalars (C++).
var_value< T > &	operator-= (const var_value< T > &b)
	The compound subtract/assignment operator for variables (C++).
var_value< T > &	operator-= (T b)
	The compound subtract/assignment operator for scalars (C++).
var_value< T > &	operator*= (const var_value< T > &b)
	The compound multiply/assignment operator for variables (C++).
var_value< T > &	operator*= (T b)
	The compound multiply/assignment operator for scalars (C++).
var_value< T > &	operator/= (const var_value< T > &b)
	The compound divide/assignment operator for variables (C++).
var_value< T > &	operator/= (T b)
	The compound divide/assignment operator for scalars (C++).

Public Attributes
vari_type *	vi_
	Pointer to the implementation of this variable.

Friends
std::ostream &	operator<< (std::ostream &os, const var_value< T > &v)
	Write the value of this autodiff variable and its adjoint to the specified output stream.

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The documentation for this class was generated from the following files:

• stan/math/rev/core/var.hpp
• stan/math/rev/core/operator_divide_equal.hpp
• stan/math/rev/core/operator_minus_equal.hpp
• stan/math/rev/core/operator_multiply_equal.hpp
• stan/math/rev/core/operator_plus_equal.hpp