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double buffered real to complex transform (idaholab#401)
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@dschwen
dschwen committed Apr 29, 2020
1 parent 8aabb42 commit 4ff3845
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Showing 4 changed files with 107 additions and 222 deletions.
55 changes: 24 additions & 31 deletions include/userobjects/FFTBufferBase.h
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Original file line number Diff line number Diff line change
Expand Up @@ -8,18 +8,24 @@

#pragma once

#include "ComplexTypes.h"
#include "ElementUserObject.h"
#include "FFTData.h"

template <typename T>
class FFTBufferBase;

#define usingFFTBufferBaseMembers \
using ElementUserObject::_perf_graph; \
using FFTBufferBase<T>::_dim; \
using FFTBufferBase<T>::_grid; \
using FFTBufferBase<T>::_buffer; \
using FFTBufferBase<T>::_start; \
using FFTBufferBase<T>::_stride; \
using FFTBufferBase<T>::_real_space_grid; \
using FFTBufferBase<T>::_reciprocal_space_grid; \
using FFTBufferBase<T>::_real_space_data; \
using FFTBufferBase<T>::_reciprocal_space_data; \
using FFTBufferBase<T>::_real_space_data_start; \
using FFTBufferBase<T>::_reciprocal_space_data_start; \
using FFTBufferBase<T>::_real_space_data_stride; \
using FFTBufferBase<T>::_reciprocal_space_data_stride; \
using FFTBufferBase<T>::_how_many

/**
Expand All @@ -28,6 +34,8 @@ class FFTBufferBase;
template <typename T>
class FFTBufferBase : public ElementUserObject
{
using ComplexT = typename ComplexType<T>::type;

public:
static InputParameters validParams();

Expand All @@ -43,31 +51,20 @@ class FFTBufferBase : public ElementUserObject
virtual void backward() = 0;
///@}

///@{ data access by index
const T & operator[](std::size_t i) const { return _buffer[i]; }
T & operator[](std::size_t i) { return _buffer[i]; }
///@}
///@{ buffer access
FFTData<T> & realSpace() { return _real_space_data; }
FFTData<ComplexT> & reciprocalSpace() { return _reciprocal_space_data; }
const FFTData<T> & realSpace() const { return _real_space_data; }
const FFTData<ComplexT> & reciprocalSpace() const { return _reciprocal_space_data; }

///@{ data access by location
///@{ real space data access by location
const T & operator()(const Point & p) const;
T & operator()(const Point & p);
///@}

///@{ convenience math operators
FFTBufferBase<T> & operator+=(FFTBufferBase<T> const & rhs);
FFTBufferBase<T> & operator-=(FFTBufferBase<T> const & rhs);
FFTBufferBase<T> & operator*=(FFTBufferBase<Real> const & rhs);
FFTBufferBase<T> & operator/=(FFTBufferBase<Real> const & rhs);
FFTBufferBase<T> & operator*=(Real rhs);
FFTBufferBase<T> & operator/=(Real rhs);
///@}

/// return the number of grid cells along each dimension without padding
const std::vector<int> & grid() const { return _grid; }

/// return the number of proper grid cells without padding
const std::size_t & size() const { return _grid_size; }

/// return the buffer dimension
const unsigned int & dim() const { return _dim; }

Expand All @@ -79,12 +76,6 @@ class FFTBufferBase : public ElementUserObject
}

protected:
/// get the addres of the first data element of the ith object in the bufefr
Real * start(std::size_t i);

/// get the number of transforms required for type T
std::size_t howMany() const;

///@{ mesh data
MooseMesh & _mesh;
unsigned int _dim;
Expand All @@ -103,15 +94,17 @@ class FFTBufferBase : public ElementUserObject
Real _cell_volume;

///@{ FFT data buffer and unpadded number of grid cells
std::vector<T> _buffer;
std::size_t _grid_size;
FFTData<T> _real_space_data;
FFTData<ComplexT> _reciprocal_space_data;
///@}

/// pointer to the start of the data
Real * _start;
Real * _real_space_data_start;
Complex * _reciprocal_space_data_start;

/// stride in units of double size
std::ptrdiff_t _stride;
std::ptrdiff_t _real_space_data_stride;
std::ptrdiff_t _reciprocal_space_data_stride;

/// optional moose sister variabe (to obtain IC from)
std::vector<const VariableValue *> _moose_variable;
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47 changes: 27 additions & 20 deletions src/executioners/SpectralExecutionerBase.C
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Original file line number Diff line number Diff line change
Expand Up @@ -57,16 +57,22 @@ SpectralExecutionerBase::execute()
_fe_problem.advanceState();

// back and forth test
auto & c = getFFTBuffer<Real>("c");
c.forward();
auto & R = getFFTBuffer<RealVectorValue>("R");
R.forward();
auto & c_buffer = getFFTBuffer<Real>("c");
auto c = c_buffer.realSpace();
c_buffer.forward();

auto & R_buffer = getFFTBuffer<RealVectorValue>("R");
auto R = R_buffer.realSpace();
R_buffer.forward();

// gradient test
auto & u = getFFTBuffer<Real>("u");
u.forward();
auto & grad_u = getFFTBuffer<RealVectorValue>("grad_u");
kVectorMultiply(u, grad_u);
auto & u_buffer = getFFTBuffer<Real>("u");
auto u = u_buffer.realSpace();
u_buffer.forward();

auto & grad_u_buffer = getFFTBuffer<RealVectorValue>("grad_u");
auto grad_u = grad_u_buffer.realSpace();
kVectorMultiply(u_buffer, grad_u_buffer);

_time_step = 1;
_fe_problem.execute(EXEC_FINAL);
Expand All @@ -75,14 +81,15 @@ SpectralExecutionerBase::execute()
_fe_problem.advanceState();

// back and forth test
c.backward();
R.backward();
c_buffer.backward();
R_buffer.backward();
R /= 10000.0;
c /= 10000.0;

// gradient test
u.backward();
grad_u.backward();
u_buffer.backward();
grad_u_buffer.backward();

u /= 10000.0;
grad_u /= 100.0;

Expand All @@ -93,23 +100,24 @@ SpectralExecutionerBase::execute()
}

void
SpectralExecutionerBase::kVectorMultiply(const FFTBufferBase<Real> & in,
FFTBufferBase<RealVectorValue> & out) const
SpectralExecutionerBase::kVectorMultiply(const FFTBufferBase<Real> & in_buffer,
FFTBufferBase<RealVectorValue> & out_buffer) const
{
mooseAssert(in_buffer.dim() == out_buffer.dim(), "Buffer dimensions must be equal");

const FFTData<Complex> & in = in_buffer.reciprocalSpace();
FFTData<ComplexVectorValue> & out = out_buffer.reciprocalSpace();
mooseAssert(in.size() == out.size(), "Buffer sizes must be equal");
mooseAssert(in.dim() == out.dim(), "Buffer dimensions must be equal");

const auto & grid = in.grid();
switch (in.dim())
const auto & grid = in_buffer.grid();
switch (in_buffer.dim())
{
case 1:
{
const int ni = grid[0];
for (int i = 0; i < ni; ++i)
{
out[i](0) = in[i] * i;
out[i](1) = 0.0;
out[i](2) = 0.0;
}
return;
}
Expand All @@ -124,7 +132,6 @@ SpectralExecutionerBase::kVectorMultiply(const FFTBufferBase<Real> & in,
{
out[index](0) = in[index] * i;
out[index](1) = in[index] * j;
out[index](2) = 0.0;
index++;
}
return;
Expand Down
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