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nx(n)?(?1/2)u(n) 2、

>> x=(-1/2).^n.*heaviside(n); >> stem(n,x,'filled')

3、x(n)?n[u(n)?u(n?5)] >> x=n.*(heaviside(n)-heaviside(t-5)); >> stem(n,x,'filled')

4 3.5 3 2.5 2 1.5 1 0.5 0 0 1 2 3 4 5 6 7 8 9 10

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4、x(n)?sin(n?/2)u(n) >> x=sin(n*pi/2).*heaviside(n); >> stem(n,x,'filled')

0.8 0.6 0.4 0.2 0 -0.2 -0.4 -0.6 -0.8 -1 0 1 2 3 4 5 6 7 8 9 10 （3）、利用MATLAB生成并绘制连续周期矩形波信号，要求周期为2，峰值为3，显示三个周期波形。

>> t=0:0.001:6; >> x=square(t*pi).*3; >> plot(t,x)

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3 2 1 0 -1 -2 -3 0

1

12 3 4 5 6

(4)、已知信号x(t)?4?t,(0?t?4),用MATLAB绘出下列信号的波形

1、

x3(t)?x1(t)?x2(t)

>> t=0:0.001:10;

>> x1=(-t+4).*(heaviside(t)-heaviside(t-4)); >> x2=sin(2*pi*t); >>x3=x1+x2; plot(t,x3)

5 4 3 2 1 0 -1 0

1 2 3 4 5 6 7 8 9

10

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2、x4(t)?x1(t)?x2(t) >> t=0:0.001:10;

>> x1=(-t+4).*(heaviside(t)-heaviside(t-4)); >> x2=sin(2*pi*t); >> x4=x1.*x2; plot(t,x4)

3 2 1 0 -1 -2 -3 -4 0

1 2 3 4 5 6 7 8 9

3、

x5(t)?x1(?t)?x1(t)

syms t;

x1=(4-t)*(heaviside(t)-heaviside(t-4)); x1=(4+t)*(heaviside(-t)-heaviside(t+4)); x5=x1+x2; ezplot(t,x5);

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