% data for Exercise Set 2.5
        
ex = input('Exercise number (1-6, 9-21)? ');
        
if ex==1
   A = [3 0;0 3], u = [1;5], v = [-4;-1]
   disp('Multiplication in MATLAB is indicated by an asterisk.  Typing the')
   disp('  command   b = A*u   will make MATLAB compute "Au" and store the result')
   disp('  in a vector  b.  If you do not need the vector for further use,')
   disp('  simply type   A*u   instead, and MATLAB will store the answer in a')
   disp('  vector called   ans   Try it.') 
elseif ex==2
   A = [2 0 0;0 2 0;0 0 2], u = [1;0;-3], v = [5;-1;4]    
elseif ex==3
   A = [1 0 -1;3 1 -5;-4 2 1], b = [0;-5;-6]    
elseif ex==4
   A = [1 2 -1;2 3 1;0 3 -8], b = [5;9;4] 
elseif ex==5
   A = [1 0 3;-2 1 -3], b = [-4;9]    
elseif ex==6  
   A = [1 0 3;0 1 -4;3 2 1;-2 -1 -2], b = [1;-5;-7;3]    
elseif ex==9
   A = [1 3 4 -3;0 1 3 -2;3 7 6 -5]    
elseif ex==10   
   A = [1 2 -7 5;0 1 -4 0;1 0 1 6;2 -1 6 8]    
elseif ex==11
   b = [1;-1;7], A = [1 3 4 -3;0 1 3 -2;3 7 6 -5]    
elseif ex==12
   b = [9;5;0;-9], A = [1 2 -7 5;0 1 -4 0;1 0 1 6;2 -1 6 8]  
elseif ex==13
   A = [-1 0;0 -1], u = [5;2], v = [-3;-1] 
elseif ex==14
   A = [0 0;0 1], u = [2;4], v = [5;-1] 
elseif ex==15
   A = [.5 0;0 .5], u = [4;2], v = [-5;-2] 
elseif ex==16
   A = [-1 0;0 1], u = [4;2], v = [-5;-2] 
elseif ex==17
   A = [0 1;1 0], u = [4;2], v = [-5;-2] 
elseif ex==18
   A = [2 0;0 1], u = [4;2], v = [-5;-2] 
elseif ex==19
   u = [1;5], y = [2;0], v = [3;1], z = [1;-4] 
elseif ex==20
   u = [1;0], y = [7;-3;1], v = [1;1], z = [2;0;4] 
elseif ex==21
   e1 = [1;0], e2 = [0;1], y1 = [3;-5], y2 = [-2;7], u = [7;6] 
else
   disp('No data for this exercise in Section 2.5.')    
end
