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Thread Subject:
Fourier Transform

Subject: Fourier Transform

From: wesley

Date: 7 Apr, 2010 14:56:06

Message: 1 of 5

College student needs help using MATLAB for Fourier Transforms. I don't want graphs just the equations solved using MATLAB. Any or all or point me do a good site. I don't want the FFT, DFT method. How is what is important.

Problems: Calculate Fourier Transforms of:

f(t)=1 for (1<=|t|<=2) and 0 otherwise

f(t)=cos wt[H(t+1/2T)-H(t-1/2t]

f(t)=exp(at) (t<=0), (a>a) and exp(-at) (t>0)

f(t)=exp(-at) sin wt H(t)

note: w is omega and T is Tau, H is Heaviside

Subject: Fourier Transform

From: Mark Shore

Date: 7 Apr, 2010 15:40:11

Message: 2 of 5

"wesley " <wes.wortman@gmail.com> wrote in message <hpi6e5$hvj$1@fred.mathworks.com>...
> College student needs help using MATLAB for Fourier Transforms. I don't want graphs just the equations solved using MATLAB. Any or all or point me do a good site. I don't want the FFT, DFT method. How is what is important.
>
> Problems: Calculate Fourier Transforms of:
>
> f(t)=1 for (1<=|t|<=2) and 0 otherwise
>
> f(t)=cos wt[H(t+1/2T)-H(t-1/2t]
>
> f(t)=exp(at) (t<=0), (a>a) and exp(-at) (t>0)
>
> f(t)=exp(-at) sin wt H(t)
>
> note: w is omega and T is Tau, H is Heaviside

Is the first week of April too late to drop the course?

Subject: Fourier Transform

From: us

Date: 7 Apr, 2010 15:44:08

Message: 3 of 5

"wesley " <wes.wortman@gmail.com> wrote in message <hpi6e5$hvj$1@fred.mathworks.com>...
> College student needs help using MATLAB for Fourier Transforms. I don't want graphs just the equations solved using MATLAB. Any or all or point me do a good site. I don't want the FFT, DFT method. How is what is important.
>
> Problems: Calculate Fourier Transforms of:
>
> f(t)=1 for (1<=|t|<=2) and 0 otherwise
>
> f(t)=cos wt[H(t+1/2T)-H(t-1/2t]
>
> f(t)=exp(at) (t<=0), (a>a) and exp(-at) (t>0)
>
> f(t)=exp(-at) sin wt H(t)
>
> note: w is omega and T is Tau, H is Heaviside

what have YOU done so far to solve YOUR particular (homework) problem...

us

Subject: Fourier Transform

From: wesley

Date: 7 Apr, 2010 16:24:05

Message: 4 of 5


EDU>> syms t;
EDU>> fourier(exp(-t^2))
 
ans =
 
pi^(1/2)/exp(w^2/4)
 

The above works but not sure how to get all the variables and preconditions into MATLAB. I'm sure it's not so bad for somebody that has figured it out and was taught by someone else. Online college sucks but I work full time on a variable schedule.

Subject: Fourier Transform

From: Mark Shore

Date: 8 Apr, 2010 14:29:04

Message: 5 of 5

"wesley " <wes.wortman@gmail.com> wrote in message <hpibj5$hlb$1@fred.mathworks.com>...
>
> EDU>> syms t;
> EDU>> fourier(exp(-t^2))
>
> ans =
>
> pi^(1/2)/exp(w^2/4)
>
>
> The above works but not sure how to get all the variables and preconditions into MATLAB. I'm sure it's not so bad for somebody that has figured it out and was taught by someone else. Online college sucks but I work full time on a variable schedule

For your second question, http://en.wikipedia.org/wiki/Heaviside_step_function has some details.

As for the rest, there are a number of accessible texts on Fourier series or transforms: Tolstov, Fourier Series; James, A student's guide to Fourier transforms; Bracewell, The Fourier Transform and its Applications (out of print), Brigham, The Fast Fourier Transform and its Applications.

While a good teacher can undoubtedly help, mastering course material is largely up to you, and this becomes increasingly true at higher levels of education.

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