% Section 3 Solutions





% --------------------

% #1  Nested Branching



x = input('input x: ');



if (x < 0)

    fx = x^2;

else

    if (x < 1)  % no need to check that x is greater than or equal

                % to 0.  If x were less than 0 the program would 

                % have entered the previous "if" block and then

                % move right to the "end" of this if-elseif-...

                % block

        fx = x;

    else % x >= 1

        if (x < 9)

            fx = 2*x;

        else % x >=9

            fx = sqrt(x);

        end

    end

end



fprintf('Result: %f\n',fx);





% --------------------

% #2 Basic Fibonacci:  Print F(1), F(2), ..., F(n)

%

n= input('Input n: ');

value1= 1;

value2= 1;

fib= 0;



if (n >= 1)

    if (n == 1)

        fprintf('%d ', value1);

    elseif (n == 2)

        fprintf('%d %d ', value1, value2);

    else

        for i=3:n

            fib= value1 + value2;

            value1= value2;

            value2= fib;

            fprintf('%d ', value2);

        end

    end

    disp(' ');

else

    disp('Must input number > 0');

end







% --------------------

% #3 Advanced Fibonacci (consecutive--not nested--loops)

% Print all integers from F(n) to F(n+1), inclusive

%

n= input('Input n: ');

value1= 1;

value2= 1;



if (n >= 1)

    if (n == 1)

        fprintf('%d ', value1)

    elseif (n==2)

	fprintf('%d %d ', value2, value1+value2)

    else

        for i=3:n+1

            fib = value1 + value2;

            value1 = value2;

            value2 = fib;

	    % At this point, value2 is F(i) and value 1 is F(i-1)

        end

        

        for i=value1:value2

            fprintf('%d ', i);

        end

    end

    disp(' ');

else

    disp('Must input number > 0');

end







% --------------------

% #4 Factors of n



n= input('Input n: ');



if (n >= 1)

    for i=2:n-1

        if (mod(n,i) == 0)

            fprintf('%d ', i);

        end

    end

    disp(' ');

else

    disp('Must input number > 0');

end





% -----------------------------

% Challenge: Prime Factors of n

%



n= input('Input n: ');



if (n >= 1)

    for i=2:n-1

        if (mod(n,i) == 0)

            j= 2;

            while  (mod(i,j) ~= 0 && j <= i)

                j = j + 1;

            end

            if (j == i)

                fprintf('%d ', i);

            end

        end

    end

    disp(' ');

else

    disp('Must input number > 0');

end