ProductOperatorSum Class Reference
[Objects with a TPS]

A sum of TensorProductOperator operators. More...

#include <quantum.h>

Collaboration diagram for ProductOperatorSum:

[legend]List of all members.

Public Member Functions
	ProductOperatorSum (const TensorProductStructure &Uinit)
	Constructor: constructs an empty sum (of no ProductOperators) on a given TensorProductStructure.
	ProductOperatorSum (const ProductOperator &oper, complex amplitude=complex(1.0, 0))
	Unit constructor: constructs the sum of exactly one ProductOperator, multiplied by a scaling factor.
	ProductOperatorSum (const ProductOperatorSum &other)
	Copy constructor: constructs an exact copy of another ProductOperatorSum.
	~ProductOperatorSum ()
	Destructor: de-allocates the component ProductOperators.
Operator &	Realize (Operator &fulloperator) const
	Realizes the dense matrix represented by this ProductOperatorSum, assigning it to the provided fulloperator.
Operator &	AddTo (Operator &fulloperator, complex amplitude=complex(1.0, 0)) const
	Realizes a scalar multiple of this ProductOperator, adding it to the provided fulloperator.
ProductOperator &	Term (itype index) const
	Returns a reference to the index'th term in the sum.
const TensorProductStructure &	TPS () const
	Returns a const reference to this ProductOperator's underlying TensorProductStructure.
itype	NTerms () const
	Returns the total number of terms in the sum.
void	ApplyTo (const State &psi, State &result) const
	Acts on the dense State psi with this ProductOperatorSum, storing the result in result.
void	ApplyAndAddTo (const State &psi, State &result, complex amplitude=complex(1.0)) const
State	operator * (State &psi) const
	Returns a new dense State which is psi transformed by this rProductOperator.
ProductOperatorSum &	operator+= (const ProductOperator &oper)
	Adds another ProductOperator to this sum, returning a reference to the result.
ProductOperatorSum &	operator+= (const ProductOperatorSum &oper)
	Adds all the terms from another ProductOperatorSum to this sum, returning a reference to the result.
ProductOperatorSum &	operator *= (complex scalar)
	Scales all the terms in this ProductOperatorSum by scalar, returning a reference to the result.
ProductOperatorSum &	operator/= (complex scalar)
	Scales all the terms in this ProductOperatorSum by 1/scalar, returning a reference to the result.

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Detailed Description

A sum of TensorProductOperator operators.

ProductOperatorSum generalizes the idea of an operator that is sparse because of its tensor product structure, making it easy to efficiently represent the sum of a small number of TensorProductOperators. A ProductOperatorSum can be constructed as an empty sum, as the sum of a single ProductOperator, or as a copy of another ProductOperatorSum. ProductOperatorSum objects are useful for representing Hamiltonians, which tend to be piecewise factorizable.

Each of the terms in the sum can be accessed as a TensorProductOperator, but the overall operator's elements are not writable (and, as of 6/06, not directly accessible at all). Things you can do with a ProductOperatorSum:

• apply it to a dense State [ApplyTo(), ApplyAndAddTo(), operator*()],
• assign or add it to a dense Operator [Realize(), AddTo()],
• access terms in the sum, [Term(), NTerms()],
• multiply or divide it by a scalar [operator*=(), operator/=()],
• add additional ProductOperator objects to the sum [operator+=()].

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Member Function Documentation

void ProductOperatorSum::ApplyTo (  const State &  psi, State &  result )  const

Acts on the dense State psi with this ProductOperatorSum, storing the result in result. WARNING: psi and result must not share any data, otherwise the result will be undefined!

void ProductOperatorSum::ApplyAndAddTo (  const State &  psi, State &  result, complex  amplitude = complex(1.0) )  const

Acts on the dense State psi with this ProductOperator; adds a scalar multiple of the result to result. WARNING: psi and result must not share any data, otherwise the result will be undefined!

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

• quantum.h
• productstate.cpp

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