void average_all_Y_columns()
{
	Worksheet wks = Project.ActiveLayer();
	int nCols,iCol = wks.AddCol();
	Dataset dsX(wks,0);
	Dataset dsY(wks,iCol);
	dsY.SetSize(dsX.GetSize());
	dsY = 0;
	for(int i=0;i<iCol;i++)
	{
		if( OKDATAOBJ_DESIGNATION_Y == wks.Columns(i).GetType() )
		{
			Dataset ds(wks,i);
			dsY += ds;
			nCols++;
		}
	}
	dsY /= nCols;
}