MFEM  v4.3.0 Finite element discretization library
mfem::DeltaCoefficient Class Reference

Delta function coefficient optionally multiplied by a weight coefficient and a scaled time dependent C-function. More...

#include <coefficient.hpp>

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## Public Member Functions

DeltaCoefficient ()
Construct a unit delta function centered at (0.0,0.0,0.0) More...

DeltaCoefficient (double x, double s)
Construct a delta function scaled by s and centered at (x,0.0,0.0) More...

DeltaCoefficient (double x, double y, double s)
Construct a delta function scaled by s and centered at (x,y,0.0) More...

DeltaCoefficient (double x, double y, double z, double s)
Construct a delta function scaled by s and centered at (x,y,z) More...

void SetDeltaCenter (const Vector &center)
Set the center location of the delta function. More...

void SetScale (double s_)
Set the scale value multiplying the delta function. More...

void SetFunction (double(*f)(double))
Set a time-dependent function that multiplies the Scale(). More...

void SetTol (double tol_)
Set the tolerance used during projection onto GridFunction to identify the Mesh vertex where the Center() of the delta function lies. (default 1e-12) More...

void SetWeight (Coefficient *w)
Set a weight Coefficient that multiplies the DeltaCoefficient. More...

const double * Center ()

double Scale ()
Return the scale factor times the optional time dependent function. Returns $$s T(t)$$ with $$T(t) = 1$$ when not set by the user. More...

double Tol ()
Return the tolerance used to identify the mesh vertices. More...

CoefficientWeight ()
See SetWeight() for description of the weight Coefficient. More...

void GetDeltaCenter (Vector &center)
Write the center of the delta function into center. More...

virtual double EvalDelta (ElementTransformation &T, const IntegrationPoint &ip)
The value of the function assuming we are evaluating at the delta center. More...

virtual double Eval (ElementTransformation &T, const IntegrationPoint &ip)
A DeltaFunction cannot be evaluated. Calling this method will cause an MFEM error, terminating the application. More...

virtual ~DeltaCoefficient ()

Public Member Functions inherited from mfem::Coefficient
Coefficient ()

void SetTime (double t)
Set the time for time dependent coefficients. More...

double GetTime ()
Get the time for time dependent coefficients. More...

double Eval (ElementTransformation &T, const IntegrationPoint &ip, double t)
Evaluate the coefficient in the element described by T at the point ip at time t. More...

virtual ~Coefficient ()

## Protected Attributes

double center [3]

double scale

double tol

Coefficientweight

int sdim

double(* tdf )(double)

Protected Attributes inherited from mfem::Coefficient
double time

## Detailed Description

Delta function coefficient optionally multiplied by a weight coefficient and a scaled time dependent C-function.

$$F(x,t) = w(x,t) s T(t) d(x - xc)$$

where w is the optional weight coefficient, s is a scale factor T is an optional time-dependent function and d is a delta function.

WARNING this cannot be used as a normal coefficient. The usual Eval method is disabled.

Definition at line 234 of file coefficient.hpp.

## Constructor & Destructor Documentation

 mfem::DeltaCoefficient::DeltaCoefficient ( )
inline

Construct a unit delta function centered at (0.0,0.0,0.0)

Definition at line 245 of file coefficient.hpp.

 mfem::DeltaCoefficient::DeltaCoefficient ( double x, double s )
inline

Construct a delta function scaled by s and centered at (x,0.0,0.0)

Definition at line 252 of file coefficient.hpp.

 mfem::DeltaCoefficient::DeltaCoefficient ( double x, double y, double s )
inline

Construct a delta function scaled by s and centered at (x,y,0.0)

Definition at line 259 of file coefficient.hpp.

 mfem::DeltaCoefficient::DeltaCoefficient ( double x, double y, double z, double s )
inline

Construct a delta function scaled by s and centered at (x,y,z)

Definition at line 266 of file coefficient.hpp.

 virtual mfem::DeltaCoefficient::~DeltaCoefficient ( )
inlinevirtual

Definition at line 318 of file coefficient.hpp.

## Member Function Documentation

 const double* mfem::DeltaCoefficient::Center ( )
inline

Return a pointer to a c-array representing the center of the delta function.

Definition at line 296 of file coefficient.hpp.

 virtual double mfem::DeltaCoefficient::Eval ( ElementTransformation & T, const IntegrationPoint & ip )
inlinevirtual

A DeltaFunction cannot be evaluated. Calling this method will cause an MFEM error, terminating the application.

Implements mfem::Coefficient.

Definition at line 316 of file coefficient.hpp.

 double mfem::DeltaCoefficient::EvalDelta ( ElementTransformation & T, const IntegrationPoint & ip )
virtual

The value of the function assuming we are evaluating at the delta center.

Definition at line 83 of file coefficient.cpp.

 void mfem::DeltaCoefficient::GetDeltaCenter ( Vector & center )

Write the center of the delta function into center.

Definition at line 77 of file coefficient.cpp.

 double mfem::DeltaCoefficient::Scale ( )
inline

Return the scale factor times the optional time dependent function. Returns $$s T(t)$$ with $$T(t) = 1$$ when not set by the user.

Definition at line 301 of file coefficient.hpp.

 void mfem::DeltaCoefficient::SetDeltaCenter ( const Vector & center )

Set the center location of the delta function.

Definition at line 69 of file coefficient.cpp.

 void mfem::DeltaCoefficient::SetFunction ( double(*)(double) f )
inline

Set a time-dependent function that multiplies the Scale().

Definition at line 279 of file coefficient.hpp.

 void mfem::DeltaCoefficient::SetScale ( double s_ )
inline

Set the scale value multiplying the delta function.

Definition at line 276 of file coefficient.hpp.

 void mfem::DeltaCoefficient::SetTol ( double tol_ )
inline

Set the tolerance used during projection onto GridFunction to identify the Mesh vertex where the Center() of the delta function lies. (default 1e-12)

Definition at line 284 of file coefficient.hpp.

 void mfem::DeltaCoefficient::SetWeight ( Coefficient * w )
inline

Set a weight Coefficient that multiplies the DeltaCoefficient.

The weight Coefficient multiplies the value returned by EvalDelta() but not the value returned by Scale(). The weight Coefficient is also used as the L2-weight function when projecting the DeltaCoefficient onto a GridFunction, so that the weighted integral of the projection is exactly equal to the Scale().

Definition at line 292 of file coefficient.hpp.

 double mfem::DeltaCoefficient::Tol ( )
inline

Return the tolerance used to identify the mesh vertices.

Definition at line 304 of file coefficient.hpp.

 Coefficient* mfem::DeltaCoefficient::Weight ( )
inline

See SetWeight() for description of the weight Coefficient.

Definition at line 307 of file coefficient.hpp.

## Member Data Documentation

 double mfem::DeltaCoefficient::center[3]
protected

Definition at line 237 of file coefficient.hpp.

 double mfem::DeltaCoefficient::scale
protected

Definition at line 237 of file coefficient.hpp.

 int mfem::DeltaCoefficient::sdim
protected

Definition at line 239 of file coefficient.hpp.

 double(* mfem::DeltaCoefficient::tdf)(double)
protected

Definition at line 240 of file coefficient.hpp.

 double mfem::DeltaCoefficient::tol
protected

Definition at line 237 of file coefficient.hpp.

 Coefficient* mfem::DeltaCoefficient::weight
protected

Definition at line 238 of file coefficient.hpp.

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