Calculating an integral threw residium question

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In summary, the conversation discusses the task of calculating the integral of a function with a complex variable. The function has two points where the denominator turns to zero and the numerator remains non-zero. The speaker also mentions a third point where both the numerator and denominator become zero, but the professor provides a formula for calculating the residuum at this point. The professor also mentions the area of integration and the need to sum the residuums of all points within this area.
  • #1
nhrock3
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i need to calculate this integral [tex]f(z)=\frac{z}{e^{2\pi iz^2}-1}\\[/tex]

in this area
[tex]\gamma _r=\left \{ |z|=r \right \},r>2[/tex]

i need to find the points which turn to zero in the denominator
and non zero in the numerator.
i got two such points
[tex]z=\pm \sqrt{n}[/tex]
by using this formula
[tex]res(\sqrt{a})=\frac{p(a)}{q(a)'}[/tex]
[tex]res(\sqrt{n})=\frac{1}{4\pi i}[/tex]
[tex]res(-\sqrt{n})=\frac{1}{4\pi i}[/tex]

the third point is z=0 but for it we have both numerator and denominator 0
i calculated the residium for it by [tex]res(f(x),a)=\lim_{x->a}(f(x)(x-a))[/tex] formula
but then
my prof says some stuff that involves the area
he says that my points are 0 +1 -1 +2^(0.5) -2^(0.5) etc.. because the denominator goes to zero
for each point have a residiu and i need to sum the residiums inside.
but here the area is not defined
its not like (by radius 3)

i don't know what point are inside the area

??
 
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  • #2
anyone?>?>
 
  • #3
sorry there is a mistake
the area is
[tex]
\gamma _r=\left \{ |z|=r \right \},n<r^2<n+1
[/tex]

and the integral is from plus to minus infinity
 
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FAQ: Calculating an integral threw residium question

What is an integral?

An integral is a mathematical concept used to calculate the area under a curve. It is represented by the symbol ∫ and is used to find the total value of a function over a certain interval.

What is a residuum?

A residuum is a mathematical term used in complex analysis. It refers to the residue or leftover value after a function is integrated over a closed loop or contour. It is usually represented by the symbol Res(f,z0) where f is the function and z0 is the point where the integral is being evaluated.

How do you calculate an integral using residuum?

To calculate an integral using residuum, you first need to identify the poles of the function (points where the function is undefined). Then, you can use the formula Res(f,z0) = limz→z0(z-z0)f(z) to find the value of the residuum at each pole. Finally, you can use the Cauchy Residue Theorem which states that the integral of a function over a closed loop is equal to 2πi times the sum of all the residuum values within the loop.

What are some common applications of calculating integrals using residuum?

Calculating integrals using residuum is commonly used in engineering, physics, and other fields of science to solve problems involving complex functions. It is also used in the field of signal processing to analyze and manipulate signals. Additionally, it is used in the study of complex systems and their behavior.

What are some tips for solving integrals using residuum?

Some tips for solving integrals using residuum include: identifying the poles of the function, understanding the Cauchy Residue Theorem, and being familiar with basic complex analysis techniques such as Cauchy's Integral Formula. It is also important to carefully evaluate the limit when finding the residuum value and to be familiar with techniques for evaluating complex integrals.

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