cell Class Reference

Order a list of points in linear time. More...

#include <cell.h>

Collaboration diagram for cell:

List of all members.

Public Member Functions
	cell ()
	Construct in bad state.
	cell (uintc N_)
	Pass the number of particles.
	~cell ()
	Memory cleanup.
void	reset (uintc N_)
	Pass the number of particles.
template<typename F >
void	eval (F &f)
	Builds the data structure.
template<typename F >
void	getsurroundingparticles (uint *const nb, uint &sz, F &f, uintc pti)
Public Attributes
uint *	count
	Tempory cell counts.
uint *	index
	Start of cell.
uint *	vi
uint *	fi
	pt->i table.
uint	W
	W columns and W rows grid.
uint	WW
	W squared.
uint	N
	Number of particles.

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Detailed Description

Order a list of points in linear time.

Provide access to the data structure

Definition at line 36 of file cell.h.

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Constructor & Destructor Documentation

cell::cell

(

)

Construct in bad state.

Definition at line 14 of file cell.cpp.

References count, fi, index, vi, W, and WW.

  : N(0)
{
  W = WW = 0;
  count = 0;
  index = 0;
  vi = 0;
  fi = 0;
}

cell::cell

(

uintc

N_

)

Pass the number of particles.

Definition at line 50 of file cell.cpp.

References reset().

{
  reset(N_);
}

cell::~cell

(

)

Memory cleanup.

Definition at line 6 of file cell.cpp.

References count, fi, index, and vi.

{
  delete[] vi;
  delete[] fi;
  delete[] count;
  delete[] index;
}

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Member Function Documentation

template<typename F >

void cell::eval

(

F &

f

)

[inline]

Builds the data structure.

Definition at line 95 of file cell.h.

References count, fi, index, N, print(), vi, W, and WW.

Referenced by test03(), and integration< D, F >::uniformgridtest().

{
  f.W = W;
assert(WW==W*W);

  for (uint i=0; i<WW; ++i)
    assert(count[i]==0);

  for (uint i=0; i<N; ++i)
  {
    fi[i] = f.index(i);
    ++count[fi[i]];
  }

  index[0] = 0;
  for (uint i=1; i<WW; ++i)
    index[i] = index[i-1]+count[i-1];


#ifdef DEBUG_CELL 
cout << "fi     ";
print(fi,fi+N);

cout << "count  ";
print(count,count+WW);

cout << "index  ";
print(index,index+WW);
#endif

  uint k;
  for (uint i=0; i<N; ++i)
  {
    k = fi[i];
    assert(k<WW);
    vi[index[k] + count[k] - 1] = i;
    --count[k];
  }

  // count[] should be all zero.
  for (uint i=0; i<WW; ++i)
    assert(count[i]==0);

#ifdef DEBUG_CELL
cout << "vi      ";
print(vi,vi+N);

cout << "count  ";
print(count,count+WW);
#endif

}

template<typename F >

void cell::getsurroundingparticles	(	uint *const	nb,
		uint &	sz,
		F &	f,
		uintc	pti
	)			[inline]

Definition at line 150 of file cell.h.

Referenced by integration< D, F >::uniformgridtest().

{
  uint * ci;
  uint n(0);
  uint c;
  uint c0;
  uint z(0);
  f.getsurroundingcells(ci,n,f.index(pti));
  for (uint i=0; i<n; ++i)
  {
    // Determine how many particles in cell k
    c0 = index[ci[i]];
    c = index[ci[i]+1]-c0;

    for (uint k=0; k<c; ++k)
      nb[z++] = vi[c0+k];
  }
  sz = z;
}

void cell::reset

(

uintc

N_

)

Pass the number of particles.

Definition at line 24 of file cell.cpp.

References count, fi, index, N, vi, W, and WW.

Referenced by cell(), and integration< D, F >::reset().

{
  if (count)
    delete[] count;
  if (vi)
    delete[] vi;
  if (index)
    delete[] index;
  if (fi)
    delete[] fi;

  N = N_;
  W = (uint)( sqrt((double)N) )+1;
  WW = W*W;
  count = new uint[WW];
  index = new uint[WW+1];
  index[WW] = N; // Sentinal value
  //  suchthat  index[k+1]-index[k] = count[k]
  vi = new uint[N];

  fi = new uint[N];

  for (uint i=0; i<WW; ++i)
    count[i]=0;
}

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Member Data Documentation

uint* cell::count

Tempory cell counts.

Definition at line 41 of file cell.h.

Referenced by cell(), eval(), reset(), and ~cell().

uint* cell::fi

pt->i table.

Definition at line 46 of file cell.h.

Referenced by cell(), eval(), reset(), and ~cell().

uint* cell::index

Start of cell.

Definition at line 43 of file cell.h.

Referenced by cell(), eval(), reset(), and ~cell().

uint cell::N

Number of particles.

Definition at line 53 of file cell.h.

Referenced by eval(), and reset().

uint* cell::vi

Definition at line 44 of file cell.h.

Referenced by cell(), eval(), reset(), and ~cell().

uint cell::W

W columns and W rows grid.

Definition at line 49 of file cell.h.

Referenced by cell(), eval(), and reset().

uint cell::WW

W squared.

Definition at line 51 of file cell.h.

Referenced by cell(), eval(), and reset().

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

• nbody/cell.h
• nbody/cell.cpp