uni20::QNum Class Reference

One irrep label together with the symmetry context needed to interpret it. More...

#include <qnum.hpp>

Public Member Functions
auto	operator== (QNum const &other) const -> bool=default
	Compare two quantum numbers for exact identity.
	QNum ()=default
	Construct an invalid quantum number.
	QNum (Symmetry sym, std::uint64_t code)
	Construct from a symmetry handle and a 63-bit inline packed code.
auto	raw_code () const -> std::uint64_t
	Return the inline packed irrep code.
auto	symmetry () const -> Symmetry
	Return the symmetry context of this quantum number.
auto	valid () const -> bool
	Return whether the quantum number carries a valid symmetry context.

Static Public Member Functions
static auto	identity (Symmetry sym) -> QNum
	Return the identity irrep of a given symmetry.

Friends
auto	coerce (QNum const &, Symmetry) -> QNum
	Coerce a quantum number into a related symmetry by named components.
auto	degree (QNum const &) -> int
	Return the integral degree of a quantum number.
auto	dual (QNum const &) -> QNum
	Return the dual irrep of a quantum number.
auto	is_identity (QNum const &) -> bool
	Return whether a quantum number is the identity irrep.
auto	make_qnum (Symmetry, std::initializer_list< std::pair< std::string_view, U1 > >) -> QNum
	Construct a packed QNum from named U(1) component values.
auto	operator+ (QNum const &, QNum const &) -> QNum
	Add two quantum numbers when the fusion result is uniquely defined.
auto	qdim (QNum const &) -> double
	Return the quantum dimension of a quantum number.
auto	to_string (QNum const &) -> std::string
	Format a quantum number as comma-separated named components.
auto	u1_component (QNum const &, std::string_view) -> U1
	Read one named U(1) component from a quantum number.

Detailed Description

One irrep label together with the symmetry context needed to interpret it.

QNum is the packed runtime label used by the tensor code. See docs/symmetry/qnum.md.

Constructor & Destructor Documentation

QNum() [1/2]

uni20::QNum::QNum ( )

default

Construct an invalid quantum number.

QNum() [2/2]

uni20::QNum::QNum ( Symmetry  sym, std::uint64_t  code  )

inlineexplicit

Construct from a symmetry handle and a 63-bit inline packed code.

Parameters

sym	Symmetry context.
code	Inline packed irrep code. Bit 63 is reserved for an out-of-line representation.

Member Function Documentation

identity()

static auto uni20::QNum::identity ( Symmetry  sym ) -> QNum

inlinestatic

Return the identity irrep of a given symmetry.

Parameters

sym	Symmetry context.

Returns

Identity quantum number.

operator==()

auto uni20::QNum::operator== ( QNum const &  other ) const -> bool=default

default

Compare two quantum numbers for exact identity.

Parameters

other

Other quantum number.

Returns

true if both symmetry context and packed code match.

raw_code()

auto uni20::QNum::raw_code ( ) const -> std::uint64_t

inline

Return the inline packed irrep code.

Returns

Canonical code in the low 63 bits.

symmetry()

auto uni20::QNum::symmetry ( ) const -> Symmetry

inline

Return the symmetry context of this quantum number.

Returns

Symmetry handle corresponding to this quantum number.

valid()

auto uni20::QNum::valid ( ) const -> bool

inline

Return whether the quantum number carries a valid symmetry context.

Returns

true if this quantum number is initialized.

Friends And Related Symbol Documentation

coerce

auto coerce ( QNum const &  q, Symmetry  target  ) -> QNum

friend

Coerce a quantum number into a related symmetry by named components.

Parameters

q	Source quantum number.
target	Target symmetry.

Returns

Coerced quantum number in the target symmetry.

degree

auto degree ( QNum const &  q ) -> int

friend

Return the integral degree of a quantum number.

Parameters

q	Quantum number to inspect.

Returns

Product of factor degrees.

dual

auto dual ( QNum const &  q ) -> QNum

friend

Return the dual irrep of a quantum number.

Parameters

q	Quantum number to dualize.

Returns

Dual quantum number in the same symmetry.

is_identity

auto is_identity ( QNum const &  q ) -> bool

friend

Return whether a quantum number is the identity irrep.

Parameters

q	Quantum number to test.

Returns

true if every factor is the identity.

make_qnum

auto make_qnum ( Symmetry  sym, std::initializer_list< std::pair< std::string_view, U1 > >  values  ) -> QNum

friend

Construct a packed QNum from named U(1) component values.

Parameters

sym	Target symmetry.
values	Named component assignments. Missing components default to the identity.

Returns

Packed quantum number in the requested symmetry.

operator+

auto operator+ ( QNum const &  lhs, QNum const &  rhs  ) -> QNum

friend

Add two quantum numbers when the fusion result is uniquely defined.

Parameters

lhs	Left operand.
rhs	Right operand.

Returns

Sum in the shared symmetry context.

qdim

auto qdim ( QNum const &  q ) -> double

friend

Return the quantum dimension of a quantum number.

Parameters

q	Quantum number to inspect.

Returns

Product of factor quantum dimensions.

to_string

auto to_string ( QNum const &  q ) -> std::string

friend

Format a quantum number as comma-separated named components.

Parameters

q	Quantum number to format.

Returns

Human-readable string form.

u1_component

auto u1_component ( QNum const &  q, std::string_view  name  ) -> U1

friend

Read one named U(1) component from a quantum number.

Parameters

q	Quantum number to decode.
name	Name of the requested symmetry component.

Returns

U(1) charge for that component.

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

• qnum.hpp