Вектор на графике

function vectarrow(p0,p1)
%Arrowline 3-D vector plot.
%   vectarrow(p0,p1) plots a line vector with arrow pointing from point p0
%   to point p1. The function can plot both 2D and 3D vector with arrow
%   depending on the dimension of the input
%
%   Example:
%       3D vector
%       p0 = [1 2 3];   % Coordinate of the first point p0
%       p1 = [4 5 6];   % Coordinate of the second point p1
%       vectarrow(p0,p1)
%
%       2D vector
%       p0 = [1 2];     % Coordinate of the first point p0
%       p1 = [4 5];     % Coordinate of the second point p1
%       vectarrow(p0,p1)
%
%   See also Vectline
%   Rentian Xiong 4-18-05
%   $Revision: 1.0
  if max(size(p0))==3
      if max(size(p1))==3
          x0 = p0(1);
          y0 = p0(2);
          z0 = p0(3);
          x1 = p1(1);
          y1 = p1(2);
          z1 = p1(3);
          plot3([x0;x1],[y0;y1],[z0;z1]);   % Draw a line between p0 and p1
          
          p = p1-p0;
          alpha = 0.1;  % Size of arrow head relative to the length of the vector
          beta = 0.1;  % Width of the base of the arrow head relative to the length
          
          hu = [x1-alpha*(p(1)+beta*(p(2)+eps)); x1; x1-alpha*(p(1)-beta*(p(2)+eps))];
          hv = [y1-alpha*(p(2)-beta*(p(1)+eps)); y1; y1-alpha*(p(2)+beta*(p(1)+eps))];
          hw = [z1-alpha*p(3);z1;z1-alpha*p(3)];
          
          hold on
          plot3(hu(:),hv(:),hw(:))  % Plot arrow head
          grid on
          xlabel('x')
          ylabel('y')
          zlabel('z')
          hold off
      else
          error('p0 and p1 must have the same dimension')
      end
  elseif max(size(p0))==2
      if max(size(p1))==2
          x0 = p0(1);
          y0 = p0(2);
          x1 = p1(1);
          y1 = p1(2);
          plot([x0;x1],[y0;y1]);   % Draw a line between p0 and p1
          
          p = p1-p0;
          alpha = 0.1;  % Size of arrow head relative to the length of the vector
          beta = 0.1;  % Width of the base of the arrow head relative to the length
          
          hu = [x1-alpha*(p(1)+beta*(p(2)+eps)); x1; x1-alpha*(p(1)-beta*(p(2)+eps))];
          hv = [y1-alpha*(p(2)-beta*(p(1)+eps)); y1; y1-alpha*(p(2)+beta*(p(1)+eps))];
          
          hold on
          plot(hu(:),hv(:))  % Plot arrow head
          grid on
          xlabel('x')
          ylabel('y')
          hold off
      else
          error('p0 and p1 must have the same dimension')
      end
  else
      error('this function only accepts 2D or 3D vector')
  end

function varargout = dsxy2figxy(varargin)
if length(varargin{1}) == 1 && ishandle(varargin{1}) ...
                            && strcmp(get(varargin{1},'type'),'axes')   
    hAx = varargin{1};
    varargin = varargin(2:end); % Remove arg 1 (axes handle)
else
    hAx = gca;
end;
 
% Remaining args are either two point locations or a position vector
if length(varargin) == 1        % Assume a 4-element position vector
    pos = varargin{1};
else
    [x,y] = deal(varargin{:});  % Assume two pairs (start, end points)
end
 
% Get limits
axun = get(hAx,'Units');
set(hAx,'Units','normalized');  % Make axes units normalized 
axpos = get(hAx,'Position');    % Get axes position
axlim = axis(hAx);              % Get the axis limits [xlim ylim (zlim)]
axwidth = diff(axlim(1:2));
axheight = diff(axlim(3:4));
 
% Transform from data space coordinates to normalized figure coordinates 
if exist('x','var')     % Transform a and return pair of points
    varargout{1} = (x - axlim(1)) * axpos(3) / axwidth + axpos(1);
    varargout{2} = (y - axlim(3)) * axpos(4) / axheight + axpos(2);
else                    % Transform and return a position rectangle
    pos(1) = (pos(1) - axlim(1)) / axwidth * axpos(3) + axpos(1);
    pos(2) = (pos(2) - axlim(3)) / axheight * axpos(4) + axpos(2);
    pos(3) = pos(3) * axpos(3) / axwidth;
    pos(4) = pos(4) * axpos(4 )/ axheight;
    varargout{1} = pos;
end
 
% Restore axes units
set(hAx,'Units',axun)