```matlab
% 产生频率为1,振幅为1的sin信号
t = 0:0.01:2*pi;
x1 = sin(t);
% 产生频率为1000,振幅为1的cos信号
x2 = cos(1000*t);
% 两个信号相乘
x3 = x1 .* x2;
% 两个信号相加
x4 = x1 + x2;
% 绘制子图
subplot(2,2,1);
plot(t,x1);
title('Sin Signal');
subplot(2,2,2);
plot(t,x2);
title('Cos Signal');
subplot(2,2,3);
plot(t,x3);
title('Multiplication of Sin and Cos Signals');
subplot(2,2,4);
plot(t,x4);
title('Addition of Sin and Cos Signals');
```