FiniteDifference Class Reference

Inheritance diagram for FiniteDifference:

Collaboration diagram for FiniteDifference:

Classes
struct	PositionChange

Public Types
enum	FiniteDiffType { FiniteDiff_LowOrder, FiniteDiff_Richardson }
using	PosChangeVector = std::vector< PositionChange >
using	ValueVector = std::vector< ValueType >
Public Types inherited from QMCTraits
enum	{ DIM = OHMMS_DIM, DIM_VGL = OHMMS_DIM + 2 }
using	QTBase = QMCTypes< OHMMS_PRECISION, DIM >
using	QTFull = QMCTypes< OHMMS_PRECISION_FULL, DIM >
using	RealType = QTBase::RealType
using	ComplexType = QTBase::ComplexType
using	ValueType = QTBase::ValueType
using	PosType = QTBase::PosType
using	GradType = QTBase::GradType
using	TensorType = QTBase::TensorType
using	IndexType = OHMMS_INDEXTYPE
	define other types More...
using	FullPrecRealType = QTFull::RealType
using	FullPrecValueType = QTFull::ValueType
using	PropertySetType = RecordNamedProperty< FullPrecRealType >
	define PropertyList_t More...
using	PtclGrpIndexes = std::vector< std::pair< int, int > >

Public Member Functions
	FiniteDifference (size_t ndim_in, FiniteDiffType fd_type=FiniteDiff_Richardson)
void	finiteDifferencePoints (RealType delta, MCWalkerConfiguration &W, PosChangeVector &positions)
	Generate points to evaluate. More...
void	computeFiniteDiff (RealType delta, PosChangeVector &positions, ValueVector &values, ParticleSet::ParticleGradient &G_fd, ParticleSet::ParticleLaplacian &L_fd)
	Compute finite difference after log psi is computed for each point. More...
void	computeFiniteDiffLowOrder (RealType delta, PosChangeVector &positions, ValueVector &values, ParticleSet::ParticleGradient &G_fd, ParticleSet::ParticleLaplacian &L_fd)
void	computeFiniteDiffRichardson (RealType delta, PosChangeVector &positions, ValueVector &values, ParticleSet::ParticleGradient &G_fd, ParticleSet::ParticleLaplacian &L_fd)

Public Attributes
const size_t	ndim
int	m_RichardsonSize
FiniteDiffType	m_fd_type

Detailed Description

Definition at line 308 of file WaveFunctionTester.cpp.

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Class Documentation

qmcplusplus::FiniteDifference::PositionChange

struct qmcplusplus::FiniteDifference::PositionChange

Definition at line 325 of file WaveFunctionTester.cpp.

Collaboration diagram for FiniteDifference::PositionChange:

Class Members
int	index
PosType	r

Member Typedef Documentation

PosChangeVector

using PosChangeVector = std::vector<PositionChange>

Definition at line 330 of file WaveFunctionTester.cpp.

ValueVector

using ValueVector = std::vector<ValueType>

Definition at line 331 of file WaveFunctionTester.cpp.

Member Enumeration Documentation

FiniteDiffType

enum FiniteDiffType

Enumerator
FiniteDiff_LowOrder
FiniteDiff_Richardson

Definition at line 311 of file WaveFunctionTester.cpp.

  {
    FiniteDiff_LowOrder,  // use simplest low-order formulas
    FiniteDiff_Richardson // use Richardson extrapolation
  };

Constructor & Destructor Documentation

FiniteDifference()

FiniteDifference ( size_t  ndim_in, FiniteDiffType  fd_type = FiniteDiff_Richardson  )

inline

Definition at line 316 of file WaveFunctionTester.cpp.

      : ndim(ndim_in), m_RichardsonSize(10), m_fd_type(fd_type)
  {}

Member Function Documentation

computeFiniteDiff()

void computeFiniteDiff	(	RealType	delta,
		PosChangeVector &	positions,
		ValueVector &	values,
		ParticleSet::ParticleGradient &	G_fd,
		ParticleSet::ParticleLaplacian &	L_fd
	)

Compute finite difference after log psi is computed for each point.

Definition at line 404 of file WaveFunctionTester.cpp.

References FiniteDifference::computeFiniteDiffLowOrder(), FiniteDifference::computeFiniteDiffRichardson(), FiniteDifference::FiniteDiff_LowOrder, FiniteDifference::FiniteDiff_Richardson, and FiniteDifference::m_fd_type.

Referenced by WaveFunctionTester::checkGradientAtConfiguration(), and WaveFunctionTester::computeNumericalGrad().

{
  assert(positions.size() == values.size());
  if (positions.size() == 0)
    return;

  ValueType logpsi = values[0];

  if (m_fd_type == FiniteDiff_LowOrder)
  {
    computeFiniteDiffLowOrder(delta, positions, values, G_fd, L_fd);
  }
  else if (m_fd_type == FiniteDiff_Richardson)
  {
    computeFiniteDiffRichardson(delta, positions, values, G_fd, L_fd);
  }
}

computeFiniteDiffLowOrder()

void computeFiniteDiffLowOrder	(	RealType	delta,
		PosChangeVector &	positions,
		ValueVector &	values,
		ParticleSet::ParticleGradient &	G_fd,
		ParticleSet::ParticleLaplacian &	L_fd
	)

Definition at line 426 of file WaveFunctionTester.cpp.

References FiniteDifference::ndim.

Referenced by FiniteDifference::computeFiniteDiff().

{
  ValueType logpsi = values[0];

  // lowest order derivative formula
  ValueType c1 = 1.0 / delta / 2.0;
  ValueType c2 = 1.0 / delta / delta;

  const RealType twoD(2 * ndim);
  const int pt_per_deriv = 2; // number of points per derivative
  for (int pt_i = 1; pt_i < values.size(); pt_i += pt_per_deriv * ndim)
  {
    GradType g0;
    ValueType lap0 = 0.0;
    for (int idim = 0; idim < ndim; idim++)
    {
      int idx            = pt_i + idim * pt_per_deriv;
      ValueType logpsi_m = values[idx];
      ValueType logpsi_p = values[idx + 1];

      g0[idim] = logpsi_p - logpsi_m;
      lap0 += logpsi_p + logpsi_m;
    }

    int iat    = positions[pt_i].index;
    GradType g = c1 * g0;
    G_fd[iat]  = g;

    ValueType lap = c2 * (lap0 - twoD * logpsi);
    //ValueType lap = c2*(lap0 - 2.0*OHMMS_DIM*logpsi);
    L_fd[iat] = lap;
  }
}

computeFiniteDiffRichardson()

void computeFiniteDiffRichardson	(	RealType	delta,
		PosChangeVector &	positions,
		ValueVector &	values,
		ParticleSet::ParticleGradient &	G_fd,
		ParticleSet::ParticleLaplacian &	L_fd
	)

Definition at line 468 of file WaveFunctionTester.cpp.

References qmcplusplus::abs(), qmcplusplus::Units::charge::e, FiniteDifference::m_RichardsonSize, FiniteDifference::ndim, and norm().

Referenced by FiniteDifference::computeFiniteDiff().

{
  RealType tol     = 1e-7;
  ValueType logpsi = values[0];

  const int pt_per_deriv = 2 * (m_RichardsonSize + 1); // number of points per derivative
  for (int pt_i = 1; pt_i < values.size(); pt_i += pt_per_deriv * ndim)
  {
    GradType g0;
    GradType gmin;
    ValueType lmin;
    std::vector<GradType> g_base(m_RichardsonSize + 1);
    std::vector<GradType> g_rich(m_RichardsonSize + 1);
    std::vector<GradType> g_prev(m_RichardsonSize + 1);

    std::vector<ValueType> l_base(m_RichardsonSize + 1);
    std::vector<ValueType> l_rich(m_RichardsonSize + 1);
    std::vector<ValueType> l_prev(m_RichardsonSize + 1);

    // Initial gradients and Laplacians at different deltas.
    RealType dd = delta;
    const ValueType ctwo(2);
    for (int inr = 0; inr < m_RichardsonSize + 1; inr++)
    {
      RealType twodd = 2 * dd;
      RealType ddsq  = dd * dd;
      l_base[inr]    = 0.0;
      for (int idim = 0; idim < ndim; idim++)
      {
        int idx            = pt_i + idim * pt_per_deriv + 2 * inr;
        ValueType logpsi_m = values[idx];
        ValueType logpsi_p = values[idx + 1];
        g_base[inr][idim]  = (logpsi_p - logpsi_m) / twodd;
        l_base[inr] += (logpsi_p + logpsi_m - ctwo * logpsi) / ddsq;
        //g_base[inr][idim] = (logpsi_p - logpsi_m)/dd/2.0;
        //l_base[inr] += (logpsi_p + logpsi_m - 2.0*logpsi)/(dd*dd);
      }
      dd = dd / 2;
    }

    // Gradient

    g_prev[0]    = g_base[0];
    RealType fac = 1;
    bool found   = false;
    for (int inr = 1; inr < m_RichardsonSize + 1; inr++)
    {
      g_rich[0] = g_base[inr];

      fac *= 4;
      for (int j = 1; j < inr + 1; j++)
      {
        g_rich[j] = g_rich[j - 1] + (g_rich[j - 1] - g_prev[j - 1]) / (fac - 1);
      }

      RealType err1 = 0.0;
      RealType norm = 0.0;
      for (int idim = 0; idim < ndim; idim++)
      {
        err1 += std::abs(g_rich[inr][idim] - g_prev[inr - 1][idim]);
        norm += std::abs(g_prev[inr - 1][idim]);
      }

      RealType err_rel = err1 / norm;

      // Not sure about the best stopping criteria
      if (err_rel < tol)
      {
        gmin  = g_rich[inr];
        found = true;
        break;
      }
      g_prev = g_rich;
    }

    if (!found)
    {
      gmin = g_rich[m_RichardsonSize];
    }


    // Laplacian
    // TODO: eliminate the copied code between the gradient and Laplacian
    //       computations.

    l_prev[0] = l_base[0];

    fac   = 1;
    found = false;
    for (int inr = 1; inr < m_RichardsonSize + 1; inr++)
    {
      l_rich[0] = l_base[inr];

      fac *= 4;
      for (int j = 1; j < inr + 1; j++)
      {
        l_rich[j] = l_rich[j - 1] + (l_rich[j - 1] - l_prev[j - 1]) / (fac - 1);
      }

      RealType err1    = std::abs(l_rich[inr] - l_prev[inr - 1]);
      RealType err_rel = std::abs(err1 / l_prev[inr - 1]);

      if (err_rel < tol)
      {
        lmin  = l_rich[inr];
        found = true;
        break;
      }
      l_prev = l_rich;
    }

    if (!found)
    {
      lmin = l_rich[m_RichardsonSize];
    }

    int iat   = positions[pt_i].index;
    G_fd[iat] = gmin;
    L_fd[iat] = lmin;
  }
}

finiteDifferencePoints()

void finiteDifferencePoints	(	RealType	delta,
		MCWalkerConfiguration &	W,
		PosChangeVector &	positions
	)

Generate points to evaluate.

Definition at line 358 of file WaveFunctionTester.cpp.

References FiniteDifference::FiniteDiff_Richardson, ParticleSet::getTotalNum(), FiniteDifference::PositionChange::index, FiniteDifference::m_fd_type, FiniteDifference::m_RichardsonSize, FiniteDifference::ndim, ParticleSet::R, and FiniteDifference::PositionChange::r.

Referenced by WaveFunctionTester::checkGradientAtConfiguration(), and WaveFunctionTester::computeNumericalGrad().

{
  // First position is the central point
  PositionChange p;
  p.index = 0;
  p.r     = W.R[0];
  positions.push_back(p);

  int nat = W.getTotalNum();
  for (int iat = 0; iat < nat; iat++)
  {
    PositionChange p;
    p.index    = iat;
    PosType r0 = W.R[iat];

    for (int idim = 0; idim < ndim; idim++)
    {
      p.r       = r0;
      p.r[idim] = r0[idim] - delta;
      positions.push_back(p);

      p.r       = r0;
      p.r[idim] = r0[idim] + delta;
      positions.push_back(p);

      if (m_fd_type == FiniteDiff_Richardson)
      {
        RealType dd = delta / 2;
        for (int nr = 0; nr < m_RichardsonSize; nr++)
        {
          p.r       = r0;
          p.r[idim] = r0[idim] - dd;
          positions.push_back(p);

          p.r       = r0;
          p.r[idim] = r0[idim] + dd;
          positions.push_back(p);

          dd = dd / 2;
        }
      }
    }
  }
}

Member Data Documentation

m_fd_type

FiniteDiffType m_fd_type

Definition at line 323 of file WaveFunctionTester.cpp.

Referenced by FiniteDifference::computeFiniteDiff(), and FiniteDifference::finiteDifferencePoints().

m_RichardsonSize

int m_RichardsonSize

Definition at line 321 of file WaveFunctionTester.cpp.

Referenced by FiniteDifference::computeFiniteDiffRichardson(), and FiniteDifference::finiteDifferencePoints().

ndim

const size_t ndim

Definition at line 320 of file WaveFunctionTester.cpp.

Referenced by FiniteDifference::computeFiniteDiffLowOrder(), FiniteDifference::computeFiniteDiffRichardson(), and FiniteDifference::finiteDifferencePoints().

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

• /home/pk7/projects/qmc/for_cron_doxygen/qmcpack/src/QMCDrivers/WaveFunctionTester.cpp