Why dosen't this Fourier Transform compute?

Question

Mariam Akhtar 2015-6-24

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/225108-why-dosen-t-this-fourier-transform-compute

评论： Image Analyst 2015-6-24

Hey! I'm trying to take a fourier transform of a particular function and Matlab doesn't seem to be able to compute it, I tried the same function in Mathmatica and it works just fine so I'm not sure whats gone wrong in this case. I used the following code:

% Program to compute the Impulse response of a third order Butterworth % filter.

syms w t

oc = 100e3*2*pi; %Cut off frequency

n = 3 %Order Number

%Transfer Function

H = oc^n /(((1i*w)+oc)*(((1i*w)^2)+(oc^2)+(2*(1i*w)*oc*sin(pi/(2*n)))));

x = fourier(H, w, t)

Impulse3 = matlabFunction(x)

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。

Answer 1

Image Analyst 2015-6-24

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/225108-why-dosen-t-this-fourier-transform-compute#answer_183811

I don't have the fourier() function. Does it show up in your help? Maybe it's in a toolbox that you have but that I don't have. Maybe that's what they call it in Mathematica but you didn't change the name when you came to MATLAB???

What I would do (because I don't have that fourier() function) is to use the fft() function . Can you try that?

Don't double space your code, just paste, highlight, and click {}Code. I fixed your formatting but please read this for next time. http://www.mathworks.com/matlabcentral/answers/13205-tutorial-how-to-format-your-question-with-markup

Also, you forgot to paste in all the red error text so I'm guessing you've never read these guidelines: http://www.mathworks.com/matlabcentral/answers/6200-tutorial-how-to-ask-a-question-on-answers-and-get-a-fast-answer. Please paste in whatever you have that tells you that "Matlab doesn't seem to be able to compute it", such as an error message.

2 个评论
显示无隐藏无

Mariam Akhtar 2015-6-24

在 MATLAB Online 中打开

Sorry! I didn't realise it wasn't a standard function, fourier() is in the symbolic maths toolbox. It doesn't come up with an error it just returns the code below. It doesn't actually perform the fourier transform.

248050213442398464*fourier(1/(w^3*(-i) - (5397215081808807*w^2)/4294967296 + w*((58259861278608895979470988302065*i)/73786976294838206464) + 34909964025886182950067141590247/140737488355328), w, t)