class TPie: public TNamed, public TAttText

 Default constructor.

 This constructor creates a pie chart when only the number of
 the slices is known. The number of slices is fixed.

 Normal constructor. The 1st and 2nd parameters are the name of the object
 and its title.

 The number of points passed at this point is used to allocate the memory.

 Slices values are given as Double_t.

 The 4th elements is an array containing, in double precision format,
 the value of each slice. It is also possible to specify the filled color
 of each slice. If the color array is not specfied the slices are colored
 using a color sequence in the standard palette.

 Normal constructor (Float_t).

 Constructor from a TH1

 Copy constructor.

 Destructor.

 Evaluate the distance to the chart in gPad.

 Returns the slice number at the pixel position (px,py).
 Returns -1 if no slice is picked.

 Used by DistancetoPrimitive.

 Draw the pie chart.

 The possible options are listed in the TPie::Paint() method.

 This method is for internal use. It is used by Execute event to draw the
 outline of "this" TPie. Used when the opaque movements are not permitted.

 Execute the mouse events.

 Returns the label of the entry number "i".

 Return the color of the slice number "i".

 Return the style use to fill the slice number "i".

 Return the line color used to outline thi "i" slice

 Return the style used to outline thi "i" slice

 Return the line width used to outline thi "i" slice

 Return the radial offset's value for the slice number "i".

 Return the value associated with the slice number "i".

 If created before by Paint option or by MakeLegend method return
 the pointer to the legend, otherwise return 0;

 Return the reference to the slice of index 'id'. There are no controls
 of memory corruption, be carefull.

 Common initialization for all constructors.
 This is a private function called to allocate the memory.

 This method create a legend that explains the contents
 of the slice for this pie-chart.

 The parameter passed reppresents the option passed to shown the slices,
 see TLegend::AddEntry() for futher details.

 The pointer of the TLegend is returned.

 Paint a Pie chart in a canvas.
 The possible option are:

 "R"   Print the labels along the central "R"adius of slices.
 "T"   Print the label in a direction "T"angent to circle that describes
       the TPie.
 "SC"  Paint the the labels with the "S"ame "C"olor as the slices.
 "3D"  Draw the pie-chart with a pseudo 3D effect.
 "NOL" No OutLine: Don't draw the slices' outlines, any property over the
       slices' line is ignored.
 ">"   Sort the slices in increasing order.
 "<"   Sort the slices in decreasing order.

 After the use of > or < options the internal order of the TPieSlices
 is changed.

 Other options changing the labels' format are described in
 TPie::SetLabelFormat().

 Save primitive as a C++ statement(s) on output stream out

 Set the value of for the pseudo 3D view angle, in degree.
 The range of the permitted values is: [0,90]

 Set the global angular offset for slices in degree [0,360]

 Set the coordinates of the circle that describe the pie:
 - the 1st and the 2nd arguments are the x and y center's coordinates.
 - the 3rd value is the pie-chart's radius.

 All the coordinates are in NDC space.

 Set slice number "i" label. The first parameter is the index of the slice,
 the other is the label text.

 Set the color for the slice's outline. "i" is the slice number.

 Set the style for the slice's outline. "i" is the slice number.

 Set the width of the slice's outline. "i" is the slice number.

 Set the color for the slice "i".

 Set the fill style for the "i" slice

 Set the distance, in the direction of the radius of the slice.

 Set the value of a slice

 Set the fill colors for all the TPie's slices.

 Set the height, in pixel, for the piechart if is drawn using
 the pseudo-3d mode.

 The default value is 20 pixel.

 This method is used to customize the label format. The format string
 must contain one of these modifiers:

 - %txt  : to print the text label associated with the slice
 - %val  : to print the numeric value of the slice
 - %frac : to print the relative fraction of this slice
 - %perc : to print the % of this slice

 ex. : mypie->SetLabelFormat("%txt (%frac)");

 Set numeric format in the label, is used if the label format
 there is the modifier %frac, in this case the value is printed
 using this format.

 The numeric format use the standard C modifier used in stdio library:
 %f, %2.1$, %e... for further documentation you can use the printf
 mapage ("man 3 printf" on linux)

 ex. : mypie->SetLabelFormat("%txt (%frac)");
       mypie->SetFractionFormat("2.1f");

 Set the labels for all the slices.

 Set the distance between the label end the external line of the TPie.

 Set the numeric format for the percent value of a slice, default: %3.1f

 Set the pie chart's radius' value.

 Set the numeric format the slices' values.
 Used by %val (see SetLabelFormat()).

 Set X value.

 Set Y value.

 Make the slices.
 If they already exist it does nothing unless force=kTRUE.

 This method, mainly intended for internal use, ordered the  slices accoording their values.
 The default (amode=kTRUE) is inscreasing order, but is also possible in decreasing order (amode=kFALSE).

 If the merge_thresold>0 the slice that contains a quantity smaller than merge_thresold are merged
 togheter