【 MATLAB 】impz函数介绍（数字滤波器的脉冲响应）

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Impulse response of digital filter

​​[h,t] = impz(b,a) [h,t] = impz(sos) [h,t] = impz(d) [h,t] = impz(...,n) [h,t] = impz(...,n,fs) impz(...)​​

​​[h，t] = impz（b，a）​​​returns the impulse response of the filter with numerator coefficients, ​​b​​​, and denominator coefficients, ​​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.