Help with found Fourier complex series of e^t

In summary, the conversation discusses finding the coefficients for a Fourier series of the function f(t) = e^t. The series is given by f(t) = ∑Cn*e^(int) and the coefficients are determined by the formula (1/2π)*∫f(t)*e^(int) dt. The person asking for help mentions trying integration by parts, but is unsure of how to proceed. The expert suggests considering the interval over which the Fourier series is needed and points out that the integral can be solved using basic techniques without the need for integration by parts.
  • #1
needved
5
0

Homework Statement


i have this function
\begin{equation}
f(t) = e^t
\end{equation}

Homework Equations


[/B]
the Fourier seria have the form
\begin{equation}
f(t) = \sum C_{n} e^{int}
\end{equation}

The Attempt at a Solution

}
[/B]
so i need to find the coeficients $c_{n}$ given by
\begin{equation}
\frac{1}{2\pi} \int_{-\pi}^{\pi} f(t) e^{int} dt
\end{equation}

my attempts are try to find the coeficients doing integration by parts but i don't have anithing. Any help here please.

thanks in advance
 
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  • #2
needved said:

Homework Statement


i have this function
\begin{equation}
f(t) = e^t
\end{equation}

Homework Equations


[/B]
the Fourier seria have the form
\begin{equation}
f(t) = \sum C_{n} e^{int}
\end{equation}

The Attempt at a Solution

}
[/B]
so i need to find the coeficients $c_{n}$ given by
\begin{equation}
\frac{1}{2\pi} \int f(t) e^{int} dt
\end{equation}

my attempts are try to find the coeficients doing integration by parts but i don't have anithing. Any help here please.

thanks in advance

(1)What is the interval over which you want the Fourier series? The series produces a periodic function of ##t##, but ##e^t## is not periodic on the whole line.
(2) You have an elementary integral that you ought to be able to solve almost by inspection. No fancy integration tools are needed, and certainly integration by parts is overkill.
 

What is a Fourier complex series?

A Fourier complex series is a mathematical representation of a periodic function using complex numbers. It is composed of an infinite sum of sine and cosine functions with different frequencies and amplitudes.

How do you find the Fourier complex series of e^t?

The Fourier complex series of e^t can be found by using the Euler's formula to express e^t in terms of sine and cosine functions. Then, the coefficients of the sine and cosine terms can be determined by integrating the function over one period.

Why is the Fourier complex series important?

The Fourier complex series is important because it allows us to approximate any periodic function with a finite number of terms. It is also used in various applications, such as signal processing, image compression, and solving differential equations.

What is the difference between Fourier complex series and Fourier series?

The main difference between Fourier complex series and Fourier series is that the former uses complex numbers while the latter uses only real numbers. This allows the Fourier complex series to represent a wider range of functions and have more accurate approximations.

Are there any limitations to using Fourier complex series?

Yes, there are limitations to using Fourier complex series. The function being approximated must be periodic, and it may not converge for certain types of discontinuous functions. Additionally, the Fourier complex series may require an infinite number of terms to accurately represent some functions.

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