Commit 1a587aa9 authored by PIACIBELLO Cyrille's avatar PIACIBELLO Cyrille

minor changes to TaylorCell, M2M added to TaylorKernel

parent a04c4775
......@@ -13,10 +13,11 @@
// "http://www.cecill.info".
// "http://www.gnu.org/licenses".
// ===================================================================================
#ifnedf FTAYLORCELL_HPP
#ifndef FTAYLORCELL_HPP
#define FTAYLORCELL_HPP
#include "../../Components/FBasicCell.hpp"
#include "../../Containers/FVector.hpp"
/**
*@author Cyrille Piacibello
......@@ -28,8 +29,30 @@
*/
template <int P>
class FTaylorCell : public FBasicCell {
protected:
//Size of Multipole Vector
static const int MultipoleSize = ((P+1)*(P+2)*(P+3))/6;
//Size of Local Vector
static const int LocalSize = ((P+1)*(P+2)*(P+3))/6;
//Multipole vector
FVector<FReal> multipole_exp = FVector(MultipoleSize);
//Local vector
FVector<FReal> local_exp = FVector(LocalSize);
public:
/**
*Default Constructor
*/
FTaylorCell(){
}
}
//Get multipole Vector
FVector * getMultipole(void)
{
return multipole_exp;
}
};
#endif
......@@ -16,7 +16,248 @@
#ifndef FTAYLORKERNEL_HPP
#define FTAYLORKERNEL_HPP
/**
* @author Cyrille Piacibello
* @class FTaylorKernel
*
* @brief This kernel is an implementation of the different operators
* needed to compute the Fast Multipole Method using Taylor Expansion
* for the Far fields interaction.
*/
template<class ParticleClass, class CellClass, class ContainerClass, int P>
class FTaylorKernel : public FAbstractKernel<ParticleClass,CellClass,ContainerClass>{
private:
//Size of the multipole and local vectors
static const int SizeVector = ((P+1)*(P+2)*(P+3))/6;
////////////////////////////////////////////////////
// Object Attributes
////////////////////////////////////////////////////
const FReal boxWidth; //< the box width at leaf level
const int treeHeight; //< The height of the tree
const FReal widthAtLeafLevel; //< width of box at leaf level
const FReal widthAtLeafLevelDiv2; //< width of box at leaf leve div 2
const FPoint boxCorner; //< position of the box corner
////////////////////////////////////////////////////
// Private method
////////////////////////////////////////////////////
/** Return the position of a leaf from its tree coordinate */
FPoint getLeafCenter(const FTreeCoordinate coordinate) const {
return FPoint(
FReal(coordinate.getX()) * widthAtLeafLevel + widthAtLeafLevelDiv2 + boxCorner.getX(),
FReal(coordinate.getY()) * widthAtLeafLevel + widthAtLeafLevelDiv2 + boxCorner.getY(),
FReal(coordinate.getZ()) * widthAtLeafLevel + widthAtLeafLevelDiv2 + boxCorner.getZ());
}
/**
* @brief Incrementation of powers in Taylor expansion
* Result : ...,[2,0,0],[1,1,0],[1,0,1]...
* 3-tuple are sorted by size and alphabetical order.
*/
void incPowers(int * const restrict a, int *const restrict b, int *const restict c)
{
int t = (*a)+(*b)+(*c);
if(t==0)
{a[0]=1;}
else{ if(t==a[0])
{a[0]--; b[0]++;}
else{ if(t==c[0])
{a[0]=t+1; c[0]=0;}
else{ if(b[0]!=0)
{b[0]--; c[0]++;}
else{
b[0]=c[0]+1;
a[0]--;
c[0]=0;
}
}
}
}
}
/**
* @brief
* Give the index of array from the corresponding powers.
*/
int powerToIdx(const int a,const int b,const int c)
{
int t,p = a+b+c;
if(p==0)
{return 0;}
else
{
int res = p*(p+1)*(p+2)/6;
t=p-a;
res+=t*(t+1)/2+c;
return res;
}
}
/* Return the factorial of a number
*/
FReal fact(const int a){
if(a<0) {
printf("Error factorial negative!! a=%d\n",a);
return FReal(0);
}
FReal result = 1;
for(int i = 1 ; i <= a ; ++i){
result *= FReal(i);
}
return result;
}
/* Return the product of factorial of 3 numbers
*/
FReal fact3int(const int a,const int b,const int c)
{
return (fact(a)*fact(b)*fact(c));
}
public:
/*Constructor, need system information*/
FTaylorKernel(const int inTreeHeight, const FReal inBoxWidth, const FPoint& inBoxCenter) :
boxWidth(inBoxWidth),
treeHeight(inTreeHeight),
widthAtLeafLevel(inBoxWidth/FReal(1 << (inTreeHeight-1))),
widthAtLeafLevelDiv2(widthAtLeafLevel/2),
boxCorner(inBoxCenter.getX()-(inBoxWidth/2),inBoxCenter.getY()-(inBoxWidth/2),inBoxCenter.getZ()-(inBoxWidth/2))
{
}
/* Default destructor
*/
virtual ~FTaylorKernel(){
}
/**P2M
* @brief Fill the Multipole with the field created by the cell
* particles.
*
* Formula :
* \f[
* M_{k} = \sum_{j=0}^{nb_particule} q_j * (x_c-x_j)^{k}*|k|!/k!
* \f]
*/
void P2M(CellClass* const pole,
const ContainerClass* const particles)
{
//Variables computed for each power of Multipole
int a=0,b=0,c=0;
FReal facto;
FReal coeff;
//Copying cell center position once and for all
const FPoint cellCenter = getLeafCenter(pole->getCoordinate());
//Iterator over the Multipole Vector
typename ContainerClass::BasicIterator iterMultipole(pole->getMultipole());
//Iterating over MutlipoleVector
while(iterMultipole.hasNotFinished())
{
// Iterator over Particles
// TODO : should be exited from the loop but BasicOperator
// class do not implement a reinit method
typename ContainerClass::ConstBasicIterator iterParticle(*particles);
//update needed values
facto=fact3int(a,b,c);
coeff=fact(a+b+c)/(facto*facto);
//Iterating over Particles
while(iterParticle.hasNotFinished())
{
const ParticleClass& particle = iterParticle.data();
const FPoint dist = (particle.getPosition()-cellCenter);
const FReal potential = particle.getPhysicalValue();
//Computation
FReal value = FReal(0);
value+=potential*FMath::pow(dist.getX(),a)*FMath::pow(dist.getY(),b)*FMath::pow(dist.getZ(),c)*coeff;
iterMultipole.setData(value);
//Go to next particle
iterParticle.gotoNext();
}
//Go to next multipole coefficient
iterMultipole.gotoNext();
incPowers(&a,&b,&c);
}
}
/**
* @brief Fill the parent multipole with the 8 values of child multipoles
*
*
*/
void M2M(CellClass* const FRestrict pole,
const CellClass*const FRestrict *const FRestrict child,
const int inLevel)
{
//Powers of expansions
int a=0,b=0,c=0;
int sum = 0;
//Indexes of powers
int idx_a,idx_b,idx_c;
//Distance from current child to parent
FReal boxSize = (boxWidth/FReal(1 << inLevel));
FReal dx = 0;
FReal dy = 0;
FReal dz = 0;
//Center point of parent cell
const FPoint cellCenter = getLeafCenter(pole->getCoordinate());
//Iteration over the eight children
int idxChild;
for(idxChild=0 ; idxChild<8 ; ++idxChild)
{
if(child[idxChild]){
//Set the distance between centers of cells
dz = (2*(1 & idxChild)-1)*boxSize;
dy = (2*((1 << 1) & idxChild)-1)*boxSize;
dx = (2*((1 << 2) & idxChild)-1)*boxSize;
//Iteration over parent multipole array
typename ContainerClass::BasicIterator iterMultipole(pole->getMultipole());
a=0;
b=0;
c=0;
sum=0;
while(iterMultipole.hasNotFinished())
{
FReal value = iterMultipole.getData();
int idMultiChild;
//Iteration over the powers to find the cell multipole
//involved in the computation of the parent multipole
for(idx_a=0 ; idx_a<=sum ; ++idx_a){
for(idx_b=0 ; idx_b<=sum-a ; ++idx_b){
for(idx_a=0 ; idx_a<sum-(a+b) ; ++idx_a){
//Computation
//Child multipole involved
idMultiChild=powerToIdx(idx_a,idx_b,idx_c);
value+=child[idxChild].getMultipole()[idMultiChild]
*FMath::pow(dx,idx_a)*FMath::pow(dy,idx_b)*FMath::pow(dz,idx_c)/fact3int(idx_a,idx_b,idx_c);
}
}
}
iterMultipole.setData(value);
iterMultipole.gotoNext();
incPowers(&a,&b,&c);
sum=a+b+c;
}
}
}
}
};
#endif FTAYLORKERNEL_HPP
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