gistfile1.matlab

            % System 4: Wien Bridge Oscillator
            K = 3; R1 = 10*10^3; R2 = R1; C1 = 10*10^-9; C2 = C1;
            tra = tf( [ K*R2*C1 0 ], [ R1*R2*C1*C2 R1*C1+R2*C2+R2*C1 1 ] );
            % Graphs
            subplot( 1, 2, 1 );
            [x,t] = step( tra );
            plot( t, x );
            title( 'Response of System 4 to a Step Input' );
            xlabel( 'Time (s)' );
            ylabel( 'Output (V)' );
            legend( 'Simulated Response', 'Theoretical Response' );
            subplot( 1, 2, 2 );
            bode( tra );