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Stan Math Library
2.6.3
probability, sampling & optimization
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The variable implementation base class. More...
#include <vari.hpp>
Public Member Functions | |
vari (const double x) | |
Construct a variable implementation from a value. More... | |
vari (const double x, bool stacked) | |
virtual | ~vari () |
Throw an illegal argument exception. More... | |
virtual void | init_dependent () |
Initialize the adjoint for this (dependent) variable to 1. More... | |
virtual void | set_zero_adjoint () |
Set the adjoint value of this variable to 0. More... | |
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chainable () | |
Construct a chainable object. More... | |
virtual | ~chainable () |
Chainables are not destructible and should go on the function call stack or be allocated with operator new. More... | |
virtual void | chain () |
Apply the chain rule to this variable based on the variables on which it depends. More... | |
Public Attributes | |
const double | val_ |
The value of this variable. More... | |
double | adj_ |
The adjoint of this variable, which is the partial derivative of this variable with respect to the root variable. More... | |
Friends | |
class | var |
std::ostream & | operator<< (std::ostream &os, const vari *v) |
Insertion operator for vari. More... | |
Additional Inherited Members | |
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static void * | operator new (size_t nbytes) |
Allocate memory from the underlying memory pool. More... | |
static void | operator delete (void *) |
Delete a pointer from the underlying memory pool. More... | |
The variable implementation base class.
A variable implementation is constructed with a constant value. It also stores the adjoint for storing the partial derivative with respect to the root of the derivative tree.
The chain() method applies the chain rule. Concrete extensions of this class will represent base variables or the result of operations such as addition or subtraction. These extended classes will store operand variables and propagate derivative information via an implementation of chain().
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inlineexplicit |
Construct a variable implementation from a value.
The adjoint is initialized to zero.
All constructed variables are added to the stack. Variables should be constructed before variables on which they depend to insure proper partial derivative propagation. During derivative propagation, the chain() method of each variable will be called in the reverse order of construction.
x | Value of the constructed variable. |
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inline |
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inlinevirtual |
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inlinevirtual |
Initialize the adjoint for this (dependent) variable to 1.
This operation is applied to the dependent variable before propagating derivatives.
Reimplemented from stan::math::chainable.
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inlinevirtual |
Set the adjoint value of this variable to 0.
Reimplemented from stan::math::chainable.
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friend |
double stan::math::vari::adj_ |
const double stan::math::vari::val_ |