【 MATLAB 】impz函式介紹（數字濾波器的脈衝響應）
這篇博文將MATLAB 幫助文件上的內容簡單的貼上，便於我寫其他博文引用，以及檢視使用。
impz
Impulse response of digital filter
Syntax
[h,t] = impz(b,a)
[h,t] = impz(sos)
[h,t] = impz(d)
[h,t] = impz(...,n)
[h,t] = impz(...,n,fs)
impz(...)
Description
[h，t] = impz（b，a）returns the impulse response of the filter with numerator coefficients, b
a. impz chooses the number of samples and returns the response in the column vector, h, and the sample times in the column vector, t. t = [0:n-1]' and n = length(t) is computed automatically.
[h,t] = impz(sos)returns the impulse response for the second-order sections matrix, sos
sos is a K-by-6 matrix, where the number of sections, K, must be greater than or equal to 2. If the number of sections is less than 2, impz considers the input to be a numerator vector. Each row of sos corresponds to the coefficients of a second order (biquad) filter. The ith row of the sos matrix corresponds to [bi(1) bi(2) bi(3) ai(1) ai(2) ai(3)][h,t] = impz(d) returns the impulse response of a digital filter, d. Use designfilt to generate d based on frequency-response specifications.
[h,t] = impz(...,n) computes n samples of the impulse response when n is an integer (t = [0:n-1]'). If n is a vector of integers, impz computes the impulse response at those integer locations, starting the response computation from 0 (and t = n or t = [0 n]). If, instead of n, you include the empty vector, [], for the second argument, the number of samples is computed automatically.
[h,t] = impz(...,n,fs) computes n samples and produces a vector t of length n so that the samples are spaced 1/fs units apart.
impz(...) with no output arguments plots the impulse response of the filter.
impz works for both real and complex input systems.