PoissonZero3DBlockedGPU Class Reference

Encapsulates core logic for using Discrete Sine Transform (implemented in terms of FFTs) to solve Poisson's equation with isolated boundaries. More...

#include <PoissonZero3DBlockedGPU.hpp>

Public Member Functions
	PoissonZero3DBlockedGPU (const int n[3], const double lo[3], const double hi[3], const int m[3], const int id[3])
long	bytes () const
void	solve (long bytes, double *density, double *potential) const
	Solve Possion's equation. To be memory efficient, this will reuse the density array as a scratch buffer.

Detailed Description

Encapsulates core logic for using Discrete Sine Transform (implemented in terms of FFTs) to solve Poisson's equation with isolated boundaries.

Restrictions

This solver makes 2 large assumptions about the resulting potential:

1. the laplacian of the potential is zero at the boundaries.
   • equivalently, the input density field must have a value of 0 at the boundaries.
   • if this is not satisfied, the density field can't be represented by a Discrete Sine Transform
2. The gradient of the potential is 0 at the boundaries
   • equivalently, the gravitation field (aka accelereation due to gravity) is 0 at the boundaries It is the caller's responsiblity to ensure that the density field passed into the solver corresponds to a gravitational potential that largely satisfies these constraints. If the caller does not satisfy these requirements, the solver will still execute. It might just provide a highly inaccurate result

Member Function Documentation

solve()

void PoissonZero3DBlockedGPU::solve	(	long	bytes,
		double *	density,
		double *	potential
	)		const

Solve Possion's equation. To be memory efficient, this will reuse the density array as a scratch buffer.

This solver will NOT provide robust solutions for an arbitrary density field. To get a robust solution, the density field MUST correspond to a potential that satisfies the assumptions outlined in the documentation for this class as a whole

Parameters

[in]	bytes	The nominal sizes of the density and potential buffers. This must be at least as large as this->bytes().
[in]	density	A device pointer to a buffer holding the values at each grid point corresponding to the RHS of Poisson's equation. After the input values are read from this buffer, it will be reused as scratch space. The contents of this buffer are unspecified once the calculation concludes.
[out]	potential	A device pointer to a buffer holding the computed gravitational potential.

Note

The bytes argument is only used to ensure that the buffers are large enough to hold intermediate results. The logic for reading the input values from density and writing the final values of potential depend entirely on the values used to configure this and entirely ignore the bytes argument.

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

• PoissonZero3DBlockedGPU.hpp