BC.cpp File Reference

This function returns the position of i, taking into account boundary conditions. More...

#include "Carmen.h"

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Functions
int	BC (int i, int AxisNo, int N)
	Returns the position of i taking into account the boundary conditions in the direction AxisNo. The number of points in this direction is N. Example: for AxisNo=1 and for N=256, i must be between 0 and 255. If i=-1, the function returns 255 for periodic boundary conditions and 0 for Neumann boundary conditions. More...

Detailed Description

This function returns the position of i, taking into account boundary conditions.

Function Documentation

int BC	(	int	i,
		int	AxisNo,
		int	N = (1<< ScaleNb)
	)

Returns the position of i taking into account the boundary conditions in the direction AxisNo. The number of points in this direction is N.
Example: for AxisNo=1 and for N=256, i must be between 0 and 255. If i=-1, the function returns 255 for periodic boundary conditions and 0 for Neumann boundary conditions.

Parameters

i	Position
AxisNo	Axis of interest
N	Defaults to (1<<ScaleNb).

Returns

int

{
  int result=-999999;

    if (AxisNo > Dimension)
        return 0;

#if defined PARMPI
    if (CMin[AxisNo] == 3) result=i;    //Periodic
    else
    {
        if (i<0) if ((coords[0]==0 && AxisNo==1) || (coords[1]==0 && AxisNo==2) || (coords[2]==0 && AxisNo==3)) result=-i-1;  //Neumann
        if (i>=N)       if ((coords[0]==CartDims[0]-1 && AxisNo==1) ||  (coords[1]==CartDims[1]-1 && AxisNo==2)
                                         || (coords[2]==CartDims[2]-1 && AxisNo==3)) result=2*N-i-1;
      if (result==-999999) result=i;    //Not the boundary, simple cell from anouther CPU
    }


#else
    if (CMin[AxisNo] == 3)
        result = (i+N)%N;                        // Periodic
    else if(CMin[AxisNo] == 2)
      result = ((i+N)/N==1)? i : (2*N-i-1)%N;  // Neumann

#endif

    return result;
}

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