I'm trying to convert a system from c2d and then from d2c but the results are not the same. Why? There is no delay!

1 次查看（过去 30 天）

sadel 2011-6-23

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/10096-i-m-trying-to-convert-a-system-from-c2d-and-then-from-d2c-but-the-results-are-not-the-same-why-the

My system is: s^2/s^3+1 My code is:

num=[1 0 0];
den=[1 0 0 1];
sys=tf(num,den)
sysd=c2d(sys,0.3)
sys2=d2c(sysd)

Why is the "sys" different from the "sys2"? Why a system like this 1/(s+1) gives correct results?

num=[1];
den=[1 1];
sys=tf(num,den)
sysd=c2d(sys,0.3)
sys2=d2c(sysd)

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

采纳的回答

zohar 2011-6-23

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/10096-i-m-trying-to-convert-a-system-from-c2d-and-then-from-d2c-but-the-results-are-not-the-same-why-the#answer_13913

在 MATLAB Online 中打开

Hi sadel

I execute your code and I got :

Transfer function:
  s^2
-------
s^3 + 1
Transfer function:
 0.2997 z^2 - 0.6 z + 0.3003
-----------------------------
z^3 - 2.987 z^2 + 3.014 z - 1
Sampling time: 0.3
Transfer function:
    s^2 - 6.217e-015 s - 1.066e-014
---------------------------------------
s^3 - 6.106e-015 s^2 - 1.377e-014 s + 1