4、已知 x(n)={1,2,3,4,5,6,7,6,5,4,3,2,1}, ,参考示例程序,绘出下列序列的波 形。 (1)x1(n)=2x(n-5)-3x(n+4) (2)x2(n)=x(3-n)+x(n)x(n-2)
时间: 2023-11-13 21:02:08 浏览: 124
好的,我明白了。关于你的问题,我来分别回答:
1. 对于 x1(n) = 2x(n-5) - 3x(n+4),可以先将其化简为:
x1(n) = 2x(n-5) - 3x(n+4)
= 2[1,2,3,4,5,6,7,6,5,4,3,2,1]n-5 - 3[1,2,3,4,5,6,7,6,5,4,3,2,1]n+4
= 2[1,2,3,4,5,6,7,6,5,4,3,2,1]n - 10 - 3[1,2,3,4,5,6,7,6,5,4,3,2,1]n + 12
= [2,4,6,8,10,12,14,12,10,8,6,4,2]n + 2
于是 x1(n) 的波形图为:
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2. 对于 x2(n) = x(3-n) * x(n) * x(n-2),可以先计算出 x(3-n),x(n),x(n-2) 的值,然后再求它们的乘积。由题可知:
x(3-n) = x(3-1) = x(2) = 3
x(n) = x(n) = [1,2,3,4,5,6,7,6,5,4,3,2,1]n
x(n-2) = x(n-2) = [1,2,3,4,5,6,7,6,5,4,3,2,1]n-2
那么有:
x2(n) = x(3-n) * x(n) * x(n-2) = 3 * [1,2,3,4,5,6,7,6,5,4,3,2,1]n * [1,2,3,4,5,6,7,6,5,4,3,2,1]n-2
化简得:
x2(n) = [1,2,3,4,5,6,7,6,5,4,3,2,1]n * [1,2,3,4,5,6,7,6,5,4,3,2,1]n-2 * 3
于是 x2(n) 的波形图为:
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