差别
这里会显示出您选择的修订版和当前版本之间的差别。
| 后一修订版 | 前一修订版 | ||
| 工程数学:z变换 [2026/02/21 15:01] – 创建 张叶安 | 工程数学:z变换 [2026/02/21 15:28] (当前版本) – [9.9 习题] 张叶安 | ||
|---|---|---|---|
| 行 153: | 行 153: | ||
| $$F(z) = \frac{-z}{z-1} + \frac{2z}{z-2}$$ | $$F(z) = \frac{-z}{z-1} + \frac{2z}{z-2}$$ | ||
| - | $$f[n] = -u[n] + 2 \cdot 2^n u[n] = (2^{n+1} - 1)u[n]$ | + | $$f[n] = -u[n] + 2 \cdot 2^n u[n] = (2^{n+1} - 1)u[n]$$ |
| ==== 9.5.3 留数法 ==== | ==== 9.5.3 留数法 ==== | ||
| 行 231: | 行 231: | ||
| 1. 求下列序列的Z变换: | 1. 求下列序列的Z变换: | ||
| - | (a) $f[n] = \left(\frac{1}{3}\right)^n u[n]$ | + | |
| - | | + | (a) $f[n] = \left(\frac{1}{3}\right)^n u[n]$ |
| - | | + | |
| + | (b) $f[n] = n(n-1)u[n]$ | ||
| + | |||
| + | (c) $f[n] = \cos\left(\frac{n\pi}{2}\right)u[n]$ | ||
| 2. 求下列Z变换的逆变换: | 2. 求下列Z变换的逆变换: | ||
| - | (a) $F(z) = \frac{1}{z-2}$,$|z| > 2$ | + | |
| - | | + | (a) $F(z) = \frac{1}{z-2}$,$|z| > 2$ |
| - | | + | |
| + | (b) $F(z) = \frac{z}{(z-1)(z-2)}$,$|z| > 2$ | ||
| + | |||
| + | (c) $F(z) = \frac{z^2}{(z-\frac{1}{2})^2}$,$|z| > \frac{1}{2}$ | ||
| 3. 用Z变换求解下列差分方程: | 3. 用Z变换求解下列差分方程: | ||
| - | (a) $y[n] - 3y[n-1] + 2y[n-2] = u[n]$,$y[-1] = y[-2] = 0$ | + | |
| - | | + | (a) $y[n] - 3y[n-1] + 2y[n-2] = u[n]$,$y[-1] = y[-2] = 0$ |
| + | |||
| + | (b) $y[n+2] - y[n] = 2^n$,$y[0] = 0$,$y[1] = 1$ | ||
| **二、思考题** | **二、思考题** | ||
| 行 251: | 行 259: | ||
| 6. 利用终值定理,确定下列 $F(z)$ 的终值是否存在,若存在求出: | 6. 利用终值定理,确定下列 $F(z)$ 的终值是否存在,若存在求出: | ||
| - | (a) $F(z) = \frac{z}{z-0.5}$ | + | |
| - | | + | (a) $F(z) = \frac{z}{z-0.5}$ |
| - | | + | |
| + | (b) $F(z) = \frac{z}{z-2}$ | ||
| + | |||
| + | (c) $F(z) = \frac{z^2}{(z-1)^2}$ | ||
| **三、应用题** | **三、应用题** | ||