% This m-file is a tutorial on loops and control structures
clear
%% Basic for loop
for j = 1:4
    v(j)=j;
end
v
%% Do operations on matrix elements using a loop
A = [ [1 2 3]' [3 2 1]' [2 1 3]'] % Define a matrix
% Re-define matrix
for j=2:3
    A(j,:) = A(j,:) - A(j-1,:)
end
%% Nested loops
for j = 1:3
    for i = 1:3
        B(i,j) = i^2-j
    end
end
%% While loop
% Find all powers of 2 less than 10000
v=1; num=1; j=1;
while num < 10000
    num = 2^j;
    v = [v ; num]; % Add num to list
    j=j+1; % Increment counter
end
v
j
%% If-elseif-else decision statements
i=6; j=21;
if i>5
    k=i;
elseif (i>1) & (j==20)
    k=5*i+j;
else
    k=1;
end
k
pause
% Break command in a for loop
for i=1:length(v)
    if v(i)>2000
        break % terminate loop
    else
        v(i) = v(i)^2+1;
    end
end
v
%% Switch-case decision statements
colour=input('colour = ','s');
switch colour
    case 'red'
        c = [1 0 0];
    case 'green'
        c = [0 1 0];
    case 'blue'
        c = [0 0 1];
    otherwise
        error('invalid choice of colour');
end
c