% data for Exercise Set 1.1
  
ex = input('Exercise number (15-26)? '); 

if ex==15   
   M = [1 5 2 1;-1 -4 1 6;1 3 -3 -9]
elseif ex==16 
   M = [0 1 1 3;3 5 9 -2;1 2 3 3]  
elseif ex==17   
   M = [1 2 0 4;-1 3 3 -2;0 1 1 0]   
elseif ex==18 
   M = [1 -5 4 -3;2 -7 3 -2;-2 1 7 -1]   
elseif ex==19 
   M = [0 1 5 -4;1 4 3 -2;2 7 1 -1]  
elseif ex==20 
   M = [2 0 -4 -10;0 1 3 2;3 5 8 -6]  
elseif ex==21 
   M = [1 -5 -4 0;-1 6 6 -3;-2 6 3 7]  
elseif ex==22 
   M = [1 2 -4 -3;-3 -5 8 7;-1 1 -3 0]  
elseif ex==23 
   M = [-2 -3 4 5;0 1 -2 4;1 3 -1 2]  
elseif ex==24 
   M = [1 -6 0 0 5;0 1 -4 1 0;-1 6 1 5 3;0 -1 5 4 0] 
elseif ex==25 
   M = [0 2 2 0 0;1 0 0 -2 -3;0 0 1 3 -4;-2 3 2 1 5] 
elseif ex==26
   M = [1 0 -2 0 -1;0 1 0 -1 2;0 -3 2 0 0;-4 0 0 7 -5]  
else 
   disp ('No data for this exercise in Section 1.1.')
end
