Need command for Continuous time fourier transform

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Ratna
Ratna 2011-9-17
回答： Juhi Maraskole 2020-9-16
Hai, I need command for Continuous time fourier transform.I know the command for Discrete time fourier transform.
One more Question, does the both results of Continuous time fourier transform and Discrete time fourier transform the same, or different.

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采纳的回答

Walter Roberson
Walter Roberson 2011-9-17
Continuous and Discrete Fourier Transform are the same in the limit case of the steps being infinitesimals.
Other than that, they cannot be compared as they work on two different kinds of information.

更多回答（5 个）

Wayne King
Wayne King 2011-9-17
Hi, If you have the Symbolic Toolbox, you can use fourier() to obtain the Fourier transform.
syms x;
f = exp(-x^2);
fourier(f)
Wayne
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Wayne King
Wayne King 2011-9-17
Hi Ratna, With all due respect, that is not correct.
Please see
>>doc symbolic/fourier
fourier
Fourier integral transform
The examples are not periodic functions of the independent variable.
Wayne
ramakrishna bathini
ramakrishna bathini 2011-9-19
Hi Wayne,
I am wrong, you are correct. But I have a function to find fourier transform over the limits.
How can I do this? As the above function fourier is for [-infinity to infinity]
Thanks,
Ratna.

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Wayne King
Wayne King 2011-9-19
Hi Ratna, You can use assume() to place limits on your variable of integration.
For example
syms x
% create Dirac distribution shifted to -1
f = dirac(x+1)
fourier(f)
% gives exp(w*i)
assume(x>0)
fourier(f)
% gives 0
Wayne
  1 个评论
Abdul Qadeer
Abdul Qadeer 2019-11-27
hi, how can we find continous time fourier and transform by using for loop. don't use built in func. plz help.

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Walter Roberson
Walter Roberson 2011-9-19
I would not recommend the approach of using assumptions. Fourier transforms are defined from -infinity to +infinity and attempts to cheat that are likely to go wrong.
Instead, multiply the function of interest by dirac(x-lowerbound) * dirac(upperbound-x) and fourier() the transformed function.
Anvesh Samineni
Anvesh Samineni 2019-10-31
continuous-time Fourier series and transforms:
p(t) = A 0 ≤ t ≤ Tp < T
0 otherwise
how can we write the code for this?
Juhi Maraskole
Juhi Maraskole 2020-9-16
Anse

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