% plot a random function with uniform step 
% sizes in [-.5, 5]

   x=rand(1,1000)-.5;
   y=cumsum(x);
   figure;
   hold on;
   grid on;
   title('Random Walk, 1000 steps');
   plot(y)

% plot a random function with step sizes
% that are -1 or +1

   x=2*round(rand(1,1000))-1; % gives -1 or +1 equally
   y=cumsum(x);
   figure;
   hold on;
   grid on;
   title('Random Walk, 1000 steps');
   plot(y)


% Use ezplot to plot sin and cos in same figure 
% Sin is plotted in blue by default, Cos in red

  figure;
  hold on;
  ezplot(@sin);
  ezplot(@cos);
  grid on;


   
% Use ezplot to plot sin and cos in same figure 
% Force interval to be [0,4 pi]

  figure;
  hold on;
  ezplot(@sin,[0,4*pi]);
  grid on;
  ezplot(@cos,[0,4*pi]);

% Use plot to plot sin and cos in same figure 
% over interval [0,4 pi]

  figure;
  hold on;
  t=[0:.1:4*pi];
  plot(t,sin(t));
  grid on;
  plot(t,cos(t));

% close all figures 

  close all;

% Use plot to plot sin and cos in same figure 
% over interval [0,4 pi]. Make Sin thick, make 
% Cos  black and dashed

  figure;
  hold on;
  t=[0:.1:4*pi];
  plot(t,sin(t),'LineWidth',5);
  grid on;
  plot(t,cos(t),'k--');

% use scatter to plot 100 random points in the 
% unit square [0,1] x [0,1]

  N=100;
  x=rand(1,N);
  y=rand(1,N);
  scatter(x,y);

% the same, but fill the dots in and 
% make them red

  N=100;
  x=rand(1,N);
  y=rand(1,N);
  scatter(x,y,'r','filled');

% Now  draw first 50 points using red dots 
% and second 50 using black +'s. Add grid 
% and title including numner of points and 
% today's date

  N=100;
  x=rand(1,N);
  y=rand(1,N);
  figure;
  hold on;
  title([num2str(N), ' Random points drawn on ', date])
  scatter(x(1:50),y(1:50),'r','filled');
  scatter(x(51:100),y(51:100),'k+');
  grid on;

% make a function that plots N random points 

function  plot_rand_pts(N)
   x=rand(1,N);
   y=rand(1,N);
   figure;
   hold on;
   title([num2str(N), ' Random points drawn on ', date)
   scatter(x,y,'k','filled');
return