Calculating Integrals with Cauchy Formula

In summary, the Cauchy formula for integrals is a powerful tool in complex analysis and contour integration. It allows for the evaluation of complex integrals using only the values of a function at points within a simple closed contour. To apply the formula, identify an analytic function on and within a simple closed contour and evaluate the integral by summing the function values at all points inside the contour. However, the formula has limitations as it can only be applied to analytic functions and simple contours. It has various real-world applications in fields such as physics, engineering, and conformal mappings.
  • #1
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Homework Statement


using cauchy integral formula calculate
[tex]\int\limits_C\frac{e^{2z}}{z^2-4}\mbox{d}z[/tex]
where [tex]C[/tex] is closed curve (point [tex]z=2[/tex] is inside)

The Attempt at a Solution


[tex]\ldots=\int\limits_C\frac{e^{2z}}{(z-2)(z+2)}\mbox{d}z=\int\limits_C\frac{f(z)}{z-2}\mbox{d}z=2\pi if(2)=2\pi i\frac{e^{2\cdot2}}{4}=\frac12\pi e^4i[/tex]
is it correct?
 
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  • #2
Yes, and yes for the other one where C is an ellipse.
 

FAQ: Calculating Integrals with Cauchy Formula

What is the Cauchy formula for integrals?

The Cauchy formula for integrals is a special case of the Cauchy integral theorem, which states that for a function f(z) that is analytic on and within a simple closed contour C, the integral of f(z) around C is equal to the sum of the values of f(z) at all points inside C.

What is the significance of the Cauchy formula for integrals?

The Cauchy formula for integrals allows for the evaluation of complex integrals using only the values of a function at points within a simple closed contour, making it a powerful tool in complex analysis and contour integration.

How do you apply the Cauchy formula for integrals?

To apply the Cauchy formula for integrals, first identify a function f(z) that is analytic on and within a simple closed contour C. Then, evaluate the integral by summing the values of f(z) at all points inside C, as stated in the formula.

What are the limitations of the Cauchy formula for integrals?

The Cauchy formula for integrals can only be applied to functions that are analytic on and within a simple closed contour. Additionally, the contour C must be simple, meaning that it cannot intersect itself or have any holes.

What are some real-world applications of the Cauchy formula for integrals?

The Cauchy formula for integrals has various applications in physics, engineering, and other fields. It is used to solve problems involving complex-valued functions, such as in electrical circuit analysis, fluid dynamics, and signal processing. It is also used in the study of conformal mappings and complex potential theory.

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