#include <triqs/utility/time_pt.hpp>

Detailed Description

A point in imaginary time, \( \tau_n \in [0, \beta] \), stored on a very fine integer grid.

Each time point is identified by an integer position \( n \in [0, N_\mathrm{max}] \) of type uint64_t and the inverse temperature \( \beta \). Its floating-point value is \( \beta * n / N_\mathrm{max} \).

Comparing two time points reduces to integer comparison, which avoids the well-known pitfalls of floating-point equality.

Various arithmetic operations are defined between time points and between time points and scalar double values.

Definition at line 60 of file time_pt.hpp.

Public Member Functions
	time_pt ()=default
	Default constructor creates the point \( \tau_0 \) for \( \beta = 0 \).
	time_pt (uint64_t n_, double beta_)
	Construct a point \( \tau_n \) from an integer grid position and the inverse temperature.
	operator double () const
	Explicit cast of \( \tau_n \) to the corresponding double value.
auto	operator<=> (time_pt const &tp) const
	Three-way comparison operator compares the integer grid positions of two time points.
time_pt &	operator= (double v)=delete
	Assigning a double is deleted to avoid accidental loss of precision.
bool	operator== (time_pt const &tp) const
	Equal-to operator compares the integer grid positions of two time points.

Static Public Member Functions
static std::string	hdf5_format ()
	Get the HDF5 format tag.

Static Public Attributes
static constexpr uint64_t	Nmax = std::numeric_limits<uint64_t>::max()
	Largest possible grid position.

Friends
time_pt	div_by_int (time_pt const &tp, size_t a)
	Divide a time point by an integer.
size_t	floor_div (time_pt const &tp1, time_pt const &tp2)
	Perform floor division between two time points.
void	h5_read (h5::group g, std::string const &name, time_pt &tp)
	Read a time_pt from HDF5.
void	h5_write (h5::group g, std::string const &name, time_pt const &tp)
	Write a time_pt to HDF5.
time_pt	mult_by_int (time_pt const &tp, size_t a)
	Multiply a time point by an integer.
time_pt	operator+ (time_pt const &tp1, time_pt const &tp2)
	Addiditon operator performs cyclic addition on \( [0, \beta] \).
time_pt	operator- (time_pt const &tp)
	Unary minus operator performs cyclic negation \( [0, \beta] \).
time_pt	operator- (time_pt const &tp1, time_pt const &tp2)
	Subtraction operator performs cyclic subtraction on \( [0, \beta] \).
std::ostream &	operator<< (std::ostream &out, time_pt const &p)
	Write a time_pt to an output stream.

Related Symbols
(Note that these are not member symbols.)
double	operator* (time_pt const &tp1, time_pt const &tp2)
	Multiplication between two time points.
double	operator/ (time_pt const &tp1, time_pt const &tp2)
	Division between two time points.

Constructor & Destructor Documentation

◆ time_pt()

triqs::utility::time_pt::time_pt	(	uint64_t	n_,
		double	beta_ )

inline

Construct a point \( \tau_n \) from an integer grid position and the inverse temperature.

Parameters

n_	Integer position \( n \in [0, N_\text{max}] \) on the grid.
beta_	Inverse temperature \( \beta \).

Definition at line 75 of file time_pt.hpp.

Member Function Documentation

◆ operator double()

triqs::utility::time_pt::operator double ( ) const

inlineexplicit

Explicit cast of \( \tau_n \) to the corresponding double value.

Returns: Floating-point value \( \beta * n / N_\mathrm{max} \).

Definition at line 162 of file time_pt.hpp.

◆ operator<=>()

auto triqs::utility::time_pt::operator<=> ( time_pt const & tp ) const

inline

Three-way comparison operator compares the integer grid positions of two time points.

Parameters

tp	Right-hand side time point.

Returns: Ordering of the two integer grid positions.

Definition at line 86 of file time_pt.hpp.

◆ operator==()

bool triqs::utility::time_pt::operator== ( time_pt const & tp ) const

inline

Equal-to operator compares the integer grid positions of two time points.

Parameters

tp	Right-hand side time point.

Returns: True if both points share the same grid position.

Definition at line 94 of file time_pt.hpp.

◆ div_by_int

time_pt div_by_int	(	time_pt const &	tp,
		size_t	a )

friend

Divide a time point by an integer.

Parameters

tp	Time point \( \tau_n \).
a	Integer divisor \( a \).

Returns: Time point with grid position \( n / a \).

Definition at line 138 of file time_pt.hpp.

◆ floor_div

size_t floor_div	(	time_pt const &	tp1,
		time_pt const &	tp2 )

friend

Perform floor division between two time points.

Parameters

tp1	Left-hand side time point \( \tau_l \).
tp2	Right-hand side time point \( \tau_r \).

Returns: Time point with grid position \( \lfloor l / r \rfloor \).

Definition at line 156 of file time_pt.hpp.

◆ h5_read

void h5_read	(	h5::group	g,
		std::string const &	name,
		time_pt &	tp )

friend

Read a time_pt from HDF5.

Parameters

g	h5::group to be read from.
name	Name of the subgroup.
tp	Time point to read into.

Definition at line 203 of file time_pt.hpp.

◆ h5_write

void h5_write	(	h5::group	g,
		std::string const &	name,
		time_pt const &	tp )

friend

Write a time_pt to HDF5.

Parameters

g	h5::group to be written to.
name	Name of the subgroup.
tp	Time point to be written.

Definition at line 188 of file time_pt.hpp.

◆ mult_by_int

time_pt mult_by_int	(	time_pt const &	tp,
		size_t	a )

friend

Multiply a time point by an integer.

Parameters

tp	Time point \( \tau_n \).
a	Integer factor \( a \).

Returns: Time point with grid position \( n * a \).

Definition at line 147 of file time_pt.hpp.

◆ operator+

time_pt operator+	(	time_pt const &	tp1,
		time_pt const &	tp2 )

friend

Addiditon operator performs cyclic addition on \( [0, \beta] \).

Parameters

tp1	Left-hand side operand \( \tau_l \).
tp2	Right-hand side operand \( \tau_r \).

Returns: Time point corresponding to the floating-point value \( (\tau_l + \tau_r) \mod \beta \).

Definition at line 103 of file time_pt.hpp.

◆ operator- [1/2]

time_pt operator- ( time_pt const & tp )

friend

Unary minus operator performs cyclic negation \( [0, \beta] \).

Parameters

tp	Time point \( \tau_n \) to negate.

Returns: Time point corresponding to the floating-point value \( \beta - \tau_n \) on the grid.

Definition at line 129 of file time_pt.hpp.

◆ operator- [2/2]

time_pt operator-	(	time_pt const &	tp1,
		time_pt const &	tp2 )

friend

Subtraction operator performs cyclic subtraction on \( [0, \beta] \).

Parameters

tp1	Left-hand side operand \( \tau_l \).
tp2	Right-hand side operand \( \tau_r \).

Returns: Time point corresponding to the floating-point value \( (\tau_l - \tau_r) \mod \beta \).

Definition at line 118 of file time_pt.hpp.

◆ operator<<

std::ostream & operator<<	(	std::ostream &	out,
		time_pt const &	p )

friend

Write a time_pt to an output stream.

Parameters

out	Output stream to write to.
p	Point to print.

Returns: Reference to the output stream.

Definition at line 171 of file time_pt.hpp.

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

triqs/utility/time_pt.hpp

Detailed Description

Public Member Functions

Static Public Member Functions

Static Public Attributes

Friends

Related Symbols

Constructor & Destructor Documentation

◆ time_pt()

Member Function Documentation

◆ operator double()

◆ operator<=>()

◆ operator==()

Friends And Related Symbol Documentation

◆ div_by_int

◆ floor_div

◆ h5_read

◆ h5_write

◆ mult_by_int

◆ operator+

◆ operator- [1/2]

◆ operator- [2/2]

◆ operator<<