material::GaussianInfluenceFn Class Reference

A class to implement Gaussian influence function. More...

#include <influenceFn.h>

Inheritance diagram for material::GaussianInfluenceFn:

Collaboration diagram for material::GaussianInfluenceFn:

Public Member Functions
	GaussianInfluenceFn (const std::vector< double > &params, const size_t &dim)
	Constructor.
double	getInfFn (const double &r) const override
	Returns the value of influence function.
double	getMoment (const size_t &i) const override
	Returns the moment of influence function.
std::string	printStr (int nt, int lvl) const override
	Returns the string containing printable information about the object.
void	print (int nt, int lvl) const override
	Prints the information about the object.
void	print () const override
	Prints the information about the object.
Public Member Functions inherited from material::BaseInfluenceFn
	BaseInfluenceFn ()=default
	Constructor.

Private Attributes
double	d_alpha
	Constants.
double	d_beta
	Constants.

Detailed Description

A class to implement Gaussian influence function.

\( J(r) = \alpha \exp(-r^2/\beta) \)

Definition at line 227 of file influenceFn.h.

Constructor & Destructor Documentation

GaussianInfluenceFn()

material::GaussianInfluenceFn::GaussianInfluenceFn	(	const std::vector< double > &	params,
		const size_t &	dim
	)

Constructor.

Parameters

params	List of parameters
dim	Dimension

Definition at line 63 of file influenceFn.cpp.

    : BaseInfluenceFn(), d_alpha(0.), d_beta(0.) {
 
  if (params.empty()) {
    // beta = 0.2 (default value)
    // choose alpha such that \int_0^1 J(r) r^d dr = 1
    d_beta = 0.2;
    if (dim == 1)
      d_alpha = 2. / (d_beta * (1. - std::exp(-1. / d_beta)));
    else if (dim == 2)
      d_alpha = (4.0 / d_beta) * 1.0 /
                (std::sqrt(M_PI * d_beta) * std::erf(1.0 / std::sqrt(d_beta)) -
                 2.0 * std::exp(-1.0 / d_beta));
    else if (dim == 3)
      d_alpha = (2.0 / d_beta) * 1.0 /
                (d_beta - (d_beta + 1.) * std::exp(-1.0 / d_beta));
  } else {
    d_alpha = params[0];
    d_beta = params[1];
  }
}

References d_alpha, and d_beta.

Member Function Documentation

getInfFn()

double material::GaussianInfluenceFn::getInfFn ( const double &  r ) const

overridevirtual

Returns the value of influence function.

Parameters

r	Reference (initial) bond length

Returns

value Influence function at r

Implements material::BaseInfluenceFn.

Definition at line 86 of file influenceFn.cpp.

                                                                  {
  return d_alpha * std::exp(-r * r / d_beta);
}

getMoment()

double material::GaussianInfluenceFn::getMoment ( const size_t &  i ) const

overridevirtual

Returns the moment of influence function.

If \( J(r) \) is the influence function for \( r\in [0,1)\) then \( i^{th}\) moment is given by

\[ M_i = \int_0^1 J(r) r^i dr. \]

Parameters

i	ith moment

Returns

moment Moment

Implements material::BaseInfluenceFn.

Definition at line 90 of file influenceFn.cpp.

                                                                   {
 
  double sq1 = std::sqrt(d_beta);
  double sq2 = std::sqrt(M_PI);
  // M_i = \int_0^1 alpha exp(-r^2/beta) r^i dr
 
  if (i == 0) {
    // M0 = 0.5 * \alpha (\beta)^(1/2) * (pi)^(1/2) * erf((1/beta)^(1/2))
 
    return 0.5 * d_alpha * sq1 * sq2 * std::erf(1. / sq1);
  } else if (i == 1) {
    // M1 = 0.5 * \alpha \beta (1 - exp(-1/beta))
 
    return 0.5 * d_alpha * d_beta * (1. - std::exp(-1. / d_beta));
  } else if (i == 2) {
    // M2 = 0.5 * \alpha (\beta)^(3/2) * [0.5 * (pi)^(1/2) erf((1/beta)^(1/2)
    // ) - (1/beta)^(1/2) * exp(-1/beta) ]
 
    return 0.5 * d_alpha * d_beta * sq1 *
           (0.5 * sq2 * std::erf(1. / sq1) -
            (1. / sq1) * std::exp(-1. / d_beta));
  } else if (i == 3) {
    // M3 = 0.5 * \alpha (\beta)^(2) * [1 - ((1/beta) + 1) * exp(-1/beta)]
 
    return 0.5 * d_alpha * d_beta * d_beta *
           (1. - (1. + 1. / d_beta) * std::exp(-1. / d_beta));
  } else {
    std::cerr << "Error: getMoment() accepts argument i from 0 to 3.\n";
    exit(1);
  }
 
 
}

Referenced by printStr().

Here is the caller graph for this function:

print() [1/2]

void material::GaussianInfluenceFn::print ( ) const

inlineoverridevirtual

Prints the information about the object.

Reimplemented from material::BaseInfluenceFn.

Definition at line 289 of file influenceFn.h.

{ print(0, 0); }

References print().

Referenced by print().

Here is the call graph for this function:

Here is the caller graph for this function:

print() [2/2]

void material::GaussianInfluenceFn::print ( int  nt, int  lvl  ) const

inlineoverridevirtual

Prints the information about the object.

Parameters

nt	Number of tabs to append before printing
lvl	Information level (higher means more information)

Reimplemented from material::BaseInfluenceFn.

Definition at line 284 of file influenceFn.h.

                                             {
    std::cout << printStr(nt, lvl);
  }

References printStr().

Here is the call graph for this function:

printStr()

std::string material::GaussianInfluenceFn::printStr ( int  nt, int  lvl  ) const

inlineoverridevirtual

Returns the string containing printable information about the object.

Parameters

nt	Number of tabs to append before printing
lvl	Information level (higher means more information)

Returns

string String containing printable information about the object

Reimplemented from material::BaseInfluenceFn.

Definition at line 263 of file influenceFn.h.

                                                     {
 
    auto tabS = util::io::getTabS(nt);
    std::ostringstream oss;
    oss << tabS << "------- GaussianInfluenceFn --------" << std::endl << std::endl;
    oss << tabS << "Gaussian function a0 * exp(-r*r / a1) with constants: a0 = "
                << d_alpha << ", a1 = " << d_beta << std::endl;
    oss << tabS << "First moment = " << getMoment(1)
        << ", second moment = " << getMoment(2)
        << ", third moment = " << getMoment(3) << std::endl;
    oss << tabS << std::endl;
 
    return oss.str();
  }

References d_alpha, d_beta, getMoment(), and util::io::getTabS().

Referenced by print().

Here is the call graph for this function:

Here is the caller graph for this function:

Field Documentation

d_alpha

double material::GaussianInfluenceFn::d_alpha

private

Constants.

Definition at line 293 of file influenceFn.h.

Referenced by GaussianInfluenceFn(), and printStr().

d_beta

double material::GaussianInfluenceFn::d_beta

private

Constants.

Definition at line 296 of file influenceFn.h.

Referenced by GaussianInfluenceFn(), and printStr().

---

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

• /home/user/project/src/material/mparticle/influenceFn.h
• /home/user/project/src/material/mparticle/influenceFn.cpp