This function select a set of M points, selected according to Type, 
  in DATA(:,:,1), and through DATA(:,:,k) 

  After starting the main routine just type the following command at the
  prompt:
  P1 = select_points(DATA,Type,M);

  [P1 P2] = select_points(DATA,'gaussian',M,2);
  P1      = select_points(DATA,'gaussian',M);

  [P1 P2] = select_points(DATA,'random',M,2);
  P1      = select_points(DATA,'random',M);

  [P1 P2] = select_points(DATA,'region',2);
  P1      = select_points(DATA,'region');

  [P1 P2 P3]= select_points(DATA,'line',3);
  P1        = select_points(DATA,'line');

  
  Input:
  DATA    is the speckle data pack. Where DATA is a 3D matrix created grouping NTIMES 
          intensity matrices with NLIN lines and NCOL columns. When N=size(DATA), then
          N(1,1) represent NLIN and
          N(1,2) represent NCOL and
          N(1,3) represent NTIMES.
          Or a image where if N=size(DATA), then
          N(1,1) represent NLIN and
          N(1,2) represent NCOL
  Type    is the type of selecting points method. These can be:
          'gaussian' - Need selecting two points; center and deviation radius.
                       This type select M points chosen randomly (Gaussian)
                       around one central point. Also is needed add an additional 
                       input parameter M, with the number of points.
          'random'   - Need selecting two points; two opposite corners.
                       This type select M points chosen uniformly random
                       between two corner points. Also is needed add an additional 
                       input parameter M, with the number of points
          'region'   - Need selecting two points; two opposite corners.
                       This type select all the pixels between two corner points.
          'line'     - Need selecting two points; begin and end.
                       This type select all the pixels in a line between two 
                       corner points.
  M        [Optional] is the number of points randomly selected.
           if Type is 'gaussian' or 'random', then M is mandatory and M will be
           the third input parameter; in other case M is not necessary and the 
           third input parameter will be Groups.
  Groups   [Optional] is the number of groups of points to be selected.
           if Type is 'gaussian' or 'random', Groups is the fourth input parameter
           in other case, Groups is the third parameter.
           the groups of points are returned as additional output parameters.
           by default Groups is 1.

  Output:
  P1      is a matrix with two columns and M lines. Thus, each line represent 
          one point in study.(line,column).
  Pi      is a matrix with two columns and M lines. Thus, each line represent 
          one point in study.(line,column). the existence of this group of points
          depend of input parameter Groups.

Package: bsltl