Show that this function is analytic

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In summary, to show that the given function is analytic, one can use the Cauchy-Riemann equations and check for the explicit appearance of z and z bar in the function after substituting x and y. Another way is to check the domain of the function, but there are cases where a function may have a complex domain but is not analytic.
  • #1
stunner5000pt
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Show that this function is analytic

[tex] \left( x + \frac{x}{x^2 + y^2} \right) + i \left( y - \frac{y}{x^2 + y^2} \right) [/tex]

now... would i substitute [tex]x = \frac{z + \overline{z}}{2} [/tex]
and
[tex] y = \frac{z - \overline{z}}{2} [/tex]

and then see if z or z bar appear exlicitly in the function??
Would that solve it??

Is there an easier way? A less Messy way?
 
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  • #2
If I recall correctly, a function is analytic if it is differentiable and if it satisfies the Cauchy-Riemann equations, perhaps you should check those?
 
  • #3
is there another way of doing it... perhaps using the substitutions i suggested above and then checking the domain of the function?
 
  • #4
stunner5000pt said:
is there another way of doing it... perhaps using the substitutions i suggested above and then checking the domain of the function?

Using the Cauchy-Riemann equations is probably the easier way.
 
  • #5
stunner5000pt said:
Show that this function is analytic

[tex] \left( x + \frac{x}{x^2 + y^2} \right) + i \left( y - \frac{y}{x^2 + y^2} \right) [/tex]

now... would i substitute [tex]x = \frac{z + \overline{z}}{2} [/tex]
and
[tex] y = \frac{z - \overline{z}}{2} [/tex]

and then see if z or z bar appear exlicitly in the function??
Would that solve it??

Is there an easier way? A less Messy way?

Your equation for y should be over 2i not just 2.
 
  • #6
stunner5000pt said:
is there another way of doing it... perhaps using the substitutions i suggested above and then checking the domain of the function?
There are complex functions whose domain is C but are nowhere analytic.
 
1)

What does it mean for a function to be analytic?

An analytic function is a mathematical function that can be expressed as a power series, and is defined in a neighborhood of each point in its domain. This means that the function has a Taylor series expansion at each point in its domain, and this series converges to the function within a certain radius.

2)

How can I determine if a function is analytic?

A function can be determined to be analytic by checking if it satisfies the Cauchy-Riemann equations, which are necessary and sufficient conditions for a function to be analytic. Alternatively, if a function can be expressed as a power series, then it is also considered to be analytic.

3)

Why is it important for a function to be analytic?

Analytic functions have many useful properties, such as being infinitely differentiable and having a unique power series representation. This makes them valuable in many areas of mathematics and science, particularly in complex analysis and physics.

4)

What are some examples of analytic functions?

Some common examples of analytic functions include polynomials, trigonometric functions, and exponential functions. Additionally, any function that can be expressed as a power series is also analytic.

5)

Can a non-analytic function be made analytic?

Yes, a non-analytic function can be made analytic through a process called analytic continuation, which extends the domain of a function to include points where it was not originally defined. This is often used in complex analysis to study the behavior of functions in the complex plane.

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