libMesh::FDMGradient< GradType > Class Template Reference

#include <fdm_gradient.h>

Inheritance diagram for libMesh::FDMGradient< GradType >:

Public Types
typedef TensorTools::DecrementRank< GradType >::type	ValType

Public Member Functions
	FDMGradient (FEMFunctionBase< ValType > &value_func, Real eps)
virtual void	init_context (const FEMContext &c) override
	Prepares a context object for use. More...
virtual std::unique_ptr< FEMFunctionBase< GradType > >	clone () const override
virtual GradType	operator() (const FEMContext &c, const Point &p, const Real time=0.) override
virtual void	operator() (const FEMContext &c, const Point &p, const Real time, DenseVector< GradType > &output) override
	Evaluation function for time-dependent vector-valued functions. More...
virtual GradType	component (const FEMContext &c, unsigned int i, const Point &p, Real time) override
virtual void	init ()
	Any post-construction initialization. More...
void	operator() (const FEMContext &, const Point &p, DenseVector< GradType > &output)
	Evaluation function for time-independent vector-valued functions. More...

Private Attributes
std::unique_ptr< FEMFunctionBase< ValType > >	_val_func
Real	_eps

Detailed Description

template<typename GradType>
class libMesh::FDMGradient< GradType >

Definition at line 30 of file fdm_gradient.h.

Member Typedef Documentation

ValType

template<typename GradType>

typedef TensorTools::DecrementRank<GradType>::type libMesh::FDMGradient< GradType >::ValType

Definition at line 33 of file fdm_gradient.h.

Constructor & Destructor Documentation

FDMGradient()

template<typename GradType>

libMesh::FDMGradient< GradType >::FDMGradient ( FEMFunctionBase< ValType > &  value_func, Real  eps  )

inline

Definition at line 35 of file fdm_gradient.h.

                         :
    _val_func(value_func.clone()), _eps(eps)
  {}

Member Function Documentation

clone()

template<typename GradType>

virtual std::unique_ptr<FEMFunctionBase<GradType> > libMesh::FDMGradient< GradType >::clone ( ) const

inlineoverridevirtual

Returns

A new copy of the function.

The new copy should be as "deep" as necessary to allow independent destruction and simultaneous evaluations of the copies in different threads.

Implements libMesh::FEMFunctionBase< GradType >.

Definition at line 43 of file fdm_gradient.h.

References libMesh::FDMGradient< GradType >::_eps, and libMesh::FDMGradient< GradType >::_val_func.

  { return std::make_unique<FDMGradient<GradType>>(*_val_func, _eps); }

component()

template<typename GradType>

virtual GradType libMesh::FDMGradient< GradType >::component ( const FEMContext &  context, unsigned int  i, const Point &  p, Real  time  )

inlineoverridevirtual

Returns

The vector component i at coordinate p and time time.

Note

Subclasses aren't required to override this, since the default implementation is based on the full vector evaluation, which is often correct.

Subclasses are recommended to override this, since the default implementation is based on a vector evaluation, which is usually unnecessarily inefficient.

Reimplemented from libMesh::FEMFunctionBase< GradType >.

Definition at line 118 of file fdm_gradient.h.

References libMesh::FDMGradient< GradType >::_eps, libMesh::FDMGradient< GradType >::_val_func, and libMesh::Real.

  {
    GradType g;

    auto & val = *_val_func;

    Real one_over_dim = Real(0.5) / _eps;

    g(0) = (val.component(c, i, p+Point(_eps), time) -
            val.component(c, i, p+Point(-_eps), time)) * one_over_dim;
#if LIBMESH_DIM > 1
    g(1) = (val.component(c, i, p+Point(0,_eps), time) -
            val.component(c, i, p+Point(0,-_eps), time)) * one_over_dim;
#endif
#if LIBMESH_DIM > 2
    g(2) = (val.component(c, i, p+Point(0,0,_eps), time) -
            val.component(c, i, p+Point(0,0,-_eps), time)) * one_over_dim;
#endif

    return g;
  }

init()

virtual void libMesh::FEMFunctionBase< GradType >::init ( )

inlinevirtualinherited

Any post-construction initialization.

Definition at line 69 of file fem_function_base.h.

{}

init_context()

template<typename GradType>

virtual void libMesh::FDMGradient< GradType >::init_context ( const FEMContext &  )

inlineoverridevirtual

Prepares a context object for use.

Most problems will want to reimplement this for efficiency, in order to call FE::get_*() as their particular function requires.

Reimplemented from libMesh::FEMFunctionBase< GradType >.

Definition at line 40 of file fdm_gradient.h.

References libMesh::FDMGradient< GradType >::_val_func.

  { _val_func->init_context(c); }

operator()() [1/3]

template<typename GradType>

virtual GradType libMesh::FDMGradient< GradType >::operator() ( const FEMContext &  , const Point &  p, const Real  time = 0.  )

inlineoverridevirtual

Returns

The scalar function value at coordinate p and time time, which defaults to zero.

Pure virtual, so you have to override it.

Implements libMesh::FEMFunctionBase< GradType >.

Definition at line 46 of file fdm_gradient.h.

References libMesh::FDMGradient< GradType >::_eps, libMesh::FDMGradient< GradType >::_val_func, and libMesh::Real.

  {
    GradType g;

    auto & val = *_val_func;

    Real one_over_dim = Real(0.5) / _eps;

    g(0) = (val(c, p+Point(_eps), time) -
            val(c, p+Point(-_eps), time)) * one_over_dim;
#if LIBMESH_DIM > 1
    g(1) = (val(c, p+Point(0,_eps), time) -
            val(c, p+Point(0,-_eps), time)) * one_over_dim;
#endif
#if LIBMESH_DIM > 2
    g(2) = (val(c, p+Point(0,0,_eps), time) -
            val(c, p+Point(0,0,-_eps), time)) * one_over_dim;
#endif

    return g;
  }

operator()() [2/3]

template<typename GradType>

virtual void libMesh::FDMGradient< GradType >::operator() ( const FEMContext &  , const Point &  p, const Real  time, DenseVector< GradType > &  output  )

inlineoverridevirtual

Evaluation function for time-dependent vector-valued functions.

Sets output values in the passed-in output DenseVector.

Pure virtual, so you have to override it.

Implements libMesh::FEMFunctionBase< GradType >.

Definition at line 70 of file fdm_gradient.h.

References libMesh::FDMGradient< GradType >::_eps, libMesh::FDMGradient< GradType >::_val_func, libMesh::make_range(), and libMesh::DenseVector< T >::size().

  {
    auto sz = output.size();
    DenseVector<ValType> v(sz);

    auto & val = *_val_func;

    val(c, p+Point(_eps), time, v);
    for (auto i : make_range(sz))
      output(i)(0) = v(i);

    val(c, p+Point(-_eps), time, v);
    for (auto i : make_range(sz))
      {
        output(i)(0) -= v(i);
        output(i)(0) /= 2;
      }

#if LIBMESH_DIM > 1
    val(c, p+Point(0,_eps), time, v);
    for (auto i : make_range(sz))
      output(i)(1) = v(i);

    val(c, p+Point(0,-_eps), time, v);
    for (auto i : make_range(sz))
      {
        output(i)(1) -= v(i);
        output(i)(1) /= 2;
      }
#endif
#if LIBMESH_DIM > 2
    val(c, p+Point(0,0,_eps), time, v);
    for (auto i : make_range(sz))
      output(i)(2) = v(i);

    val(c, p+Point(0,0,-_eps), time, v);
    for (auto i : make_range(sz))
      {
        output(i)(2) -= v(i);
        output(i)(2) /= 2;
      }
#endif
  }

operator()() [3/3]

void libMesh::FEMFunctionBase< GradType >::operator() ( const FEMContext &  context, const Point &  p, DenseVector< GradType > &  output  )

inlineinherited

Evaluation function for time-independent vector-valued functions.

Sets output values in the passed-in output DenseVector.

Definition at line 149 of file fem_function_base.h.

{
  // Call the time-dependent function with t=0.
  this->operator()(context, p, 0., output);
}

Member Data Documentation

_eps

template<typename GradType>

Real libMesh::FDMGradient< GradType >::_eps

private

Definition at line 147 of file fdm_gradient.h.

Referenced by libMesh::FDMGradient< GradType >::clone(), libMesh::FDMGradient< GradType >::component(), and libMesh::FDMGradient< GradType >::operator()().

_val_func

template<typename GradType>

std::unique_ptr<FEMFunctionBase<ValType> > libMesh::FDMGradient< GradType >::_val_func

private

Definition at line 145 of file fdm_gradient.h.

Referenced by libMesh::FDMGradient< GradType >::clone(), libMesh::FDMGradient< GradType >::component(), libMesh::FDMGradient< GradType >::init_context(), and libMesh::FDMGradient< GradType >::operator()().

---

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

• include/numerics/fdm_gradient.h