ewald Class Reference

Ewald correction functionality. More...

#include <ewald.h>

Inherits intposconvert, io_streamcount, and setcomm.

Classes
struct	ewald_header

Public Types
enum	interpolate_options { POINTMASS , MULTIPOLES , LONGRANGE_FORCETEST }

Public Member Functions
	ewald (void)
void	ewald_init (void)
	This function initializes tables with the correction force and the correction potential due to the periodic images of a point mass located at the origin. More...
void	ewald_corr (double dx, double dy, double dz, enum interpolate_options, ewald_data &fper)
void	ewald_corr_exact (double dx, double dy, double dz, enum interpolate_options flag, ewald_data &fper)
void	ewald_gridlookup (const MyIntPosType *p_intpos, const MyIntPosType *target_intpos, enum interpolate_options flag, ewald_data &fper)
double	ewald_D0 (double x, double y, double z)
	This function computes the potential correction term by means of Ewald summation. More...
vector< double >	ewald_D1 (double x, double y, double z)
	This function computes the force correction term (difference between full force of infinite lattice and nearest image) by Ewald summation. More...
symtensor2< double >	ewald_D2 (double x, double y, double z)
symtensor3< double >	ewald_D3 (double x, double y, double z)
symtensor4< double >	ewald_D4 (double x, double y, double z)
symtensor5< double >	ewald_D5 (double x, double y, double z)
symtensor6< double >	ewald_D6 (double x, double y, double z)
symtensor7< double >	ewald_D7 (double x, double y, double z)
ewaldtensor6< double >	ewald_P6 (void)
ewaldtensor8< double >	ewald_P8 (void)
ewaldtensor10< double >	ewald_P10 (void)
Public Member Functions inherited from intposconvert
void	constrain_intpos (MyIntPosType *pos)
template<typename T >
void	diff_intpos_to_pos (MyIntPosType *a, MyIntPosType *b, T *posdiff, offset_tuple off=0)
MyIntPosType	nearest_image_intpos_to_intpos_X (const MyIntPosType a, const MyIntPosType b)
MyIntPosType	nearest_image_intpos_to_intpos_Y (const MyIntPosType a, const MyIntPosType b)
MyIntPosType	nearest_image_intpos_to_intpos_Z (const MyIntPosType a, const MyIntPosType b)
template<typename T >
void	nearest_image_intpos_to_pos (const MyIntPosType *const a, const MyIntPosType *const b, T *posdiff)
void	nearest_image_intpos_to_absolute_intdist (const MyIntPosType *a, const MyIntPosType *b, MyIntPosType *delta)
template<typename T >
MySignedIntPosType	pos_to_signedintpos (T posdiff)
template<typename T >
void	pos_to_signedintpos (T *posdiff, MySignedIntPosType *intpos)
template<typename T >
void	signedintpos_to_pos (MySignedIntPosType *intpos, T *pos)
double	signedintpos_to_distanceorigin (MySignedIntPosType *intpos)
template<typename T >
void	intpos_to_pos (MyIntPosType *intpos, T *posdiff)
void	intpos_to_intpos (MyIntPosType *intpos, MyIntPosType *xyz)
template<typename T >
T	constrain_pos (T pos)
template<typename T >
void	pos_to_intpos (T *posdiff, MyIntPosType *intpos)
Public Member Functions inherited from io_streamcount
size_t	my_fwrite (const void *ptr, size_t size, size_t nmemb, FILE *stream)
	A wrapper for the fwrite() function. More...
size_t	my_fread (void *ptr, size_t size, size_t nmemb, FILE *stream)
	A wrapper for the fread() function. More...
void	reset_io_byte_count (void)
long long	get_io_byte_count (void)
Public Member Functions inherited from setcomm
	setcomm (MPI_Comm Comm)
	setcomm (const char *str)
void	initcomm (MPI_Comm Comm)
void	mpi_printf (const char *fmt,...)
void	determine_compute_nodes (void)

Additional Inherited Members
Public Attributes inherited from intposconvert
MyReal	FacIntToCoord
MyReal	FacCoordToInt
MyReal	RegionLen
MyReal	RegionCorner [3]
MyReal	RegionCenter [3]
Public Attributes inherited from io_streamcount
long long	byte_count = 0
Public Attributes inherited from setcomm
MPI_Comm	Communicator
int	NTask
int	ThisTask
int	PTask
int	ThisNode
int	NumNodes = 0
int	TasksInThisNode
int	RankInThisNode
int	MinTasksPerNode
int	MaxTasksPerNode
long long	MemoryOnNode
long long	SharedMemoryOnNode

Detailed Description

Ewald correction functionality.

This class collects all the functionality provided for Ewald table lookups.

Definition at line 53 of file ewald.h.

Member Enumeration Documentation

interpolate_options

enum interpolate_options

Enumerator
POINTMASS
MULTIPOLES
LONGRANGE_FORCETEST

Definition at line 65 of file ewald.h.

Constructor & Destructor Documentation

ewald()

ewald ( void  )

inline

Definition at line 56 of file ewald.h.

Member Function Documentation

ewald_corr()

void ewald_corr	(	double	dx,
		double	dy,
		double	dz,
		enum	interpolate_options,
		ewald_data &	fper
	)

ewald_corr_exact()

void ewald_corr_exact	(	double	dx,
		double	dy,
		double	dz,
		enum interpolate_options	flag,
		ewald_data &	fper
	)

ewald_D0()

double ewald_D0	(	double	x,
		double	y,
		double	z
	)

This function computes the potential correction term by means of Ewald summation.

Parameters

x,y,z

contains the distance vector for which the correction term should be computed

Returns

the correction term

Definition at line 705 of file ewald.cc.

ewald_D1()

vector< double > ewald_D1	(	double	x,
		double	y,
		double	z
	)

This function computes the force correction term (difference between full force of infinite lattice and nearest image) by Ewald summation.

Parameters

x,y,z	contains the distance vector for which the correction force should be computed
force	array will containing the correction force

Definition at line 898 of file ewald.cc.

ewald_D2()

symtensor2< double > ewald_D2	(	double	x,
		double	y,
		double	z
	)

Definition at line 1090 of file ewald.cc.

ewald_D3()

symtensor3< double > ewald_D3	(	double	x,
		double	y,
		double	z
	)

Definition at line 1312 of file ewald.cc.

ewald_D4()

symtensor4< double > ewald_D4	(	double	x,
		double	y,
		double	z
	)

Definition at line 1550 of file ewald.cc.

ewald_D5()

symtensor5< double > ewald_D5	(	double	x,
		double	y,
		double	z
	)

Definition at line 1694 of file ewald.cc.

ewald_D6()

symtensor6< double > ewald_D6	(	double	x,
		double	y,
		double	z
	)

Definition at line 1845 of file ewald.cc.

ewald_D7()

symtensor7< double > ewald_D7	(	double	x,
		double	y,
		double	z
	)

Definition at line 2011 of file ewald.cc.

ewald_gridlookup()

void ewald_gridlookup	(	const MyIntPosType *	p_intpos,
		const MyIntPosType *	target_intpos,
		enum interpolate_options	flag,
		ewald_data &	fper
	)

Definition at line 355 of file ewald.cc.

ewald_init()

void ewald_init

(

void

)

This function initializes tables with the correction force and the correction potential due to the periodic images of a point mass located at the origin.

This file contains the computation of the Ewald correction table, and the corresponding lookup functions.

in D0phi we store the correction potential:

phi = 1/x + pi/alpha^2 - sum_q (erfc(alpha |x-q|)/|x-q|) - 4pi/V sum_k exp(-k^2/(4alpha^2))/k^2 cos(k*x)

in D1phi we store the first derivative of correction potential

dphi/dx_i

in D2phi we store the correction tensor (second derivatives of correction potential)

d2phi/(dx_i dx_j)

in D3phi we store the third order correction tensor (third derivatives of correction potential)

d3phi/(dx_i dx_j dx_k)

and so on also for D4phi and D5phi

These corrections are obtained by Ewald summation. (See for example Hernquist, Bouchet, Suto, ApJS, 1991, 75, 231) The correction fields are used to obtain the full periodic force if periodic boundaries combined with the pure tree algorithm are used. For the TreePM/FMM-PM algorithms, the Ewald correction is not used.

The correction fields are stored on disk once they are computed. If a corresponding file is found, they are loaded from disk to speed up the initialization. The Ewald summation issrc/gravtree_forcetest.c done in parallel, i.e. the processors share the work to compute the tables if needed.

Definition at line 69 of file ewald.cc.

ewald_P10()

ewaldtensor10< double > ewald_P10

(

void

)

ewald_P6()

ewaldtensor6< double > ewald_P6

(

void

)

ewald_P8()

ewaldtensor8< double > ewald_P8

(

void

)

---

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

• src/gravity/ewald.h
• src/gravity/ewald.cc