Checking if a function is analytic or entire

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In summary, the conversation discusses the confusion between the use of the terms "holomorphic" and "analytic" in complex analysis. The speaker is unsure of the best way to check if a function is analytic and asks if there are any useful tricks or theorems to simplify the task. Additionally, they inquire about determining if a function is entire, and mention that certain functions, such as polynomials and trigonometric functions, are known to be entire.
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To begin, I think I might be using holomorphic and analytic (incorrectly) interchangeably. When I think of analytic I think of something being able to be represented locally by a power series. holomorphic however makes me think of a function being complex differentiable locally. I am a bit confused because they seem to be used interchangeably in complex analysis and that one implies the other.


Now my question, what is the best way to check that a function is analytic?/ I know this is an incredibly basic question and I look for answers but I just don't seem to find, for example, just a theorem I can apply. I know I have the C-R equations but if they are satisfied that only gaurantees the function is holomorphic at that point. To be analytic at a point, it should be complex differentiable in an entire open set containing the point.


Are there any useful little tricks to check for this? Or really good theorems to apply? And similarly with a function being entire (holomorphic everywhere?) is it just kind of an issue of analyzing the function and figuring it out (and plus I know say, polys are entire, cosz, sinz, and e^z are entire so combinations of them will be) or are there any hard and fast theorems I can apply that simplify the task?
 
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Related to Checking if a function is analytic or entire

1. How do you determine if a function is analytic?

To determine if a function is analytic, you must check if it is differentiable at every point in its domain. If the function is differentiable at every point, it is considered to be analytic.

2. What is the difference between an analytic and an entire function?

An analytic function is differentiable at every point in its domain, while an entire function is analytic and also defined for all complex numbers. In other words, an entire function is a type of analytic function that is defined on the entire complex plane.

3. Can a function be analytic but not entire?

Yes, a function can be analytic but not entire. For example, a function may have singularities or poles that make it undefined at certain points in the complex plane, but it may still be differentiable at all other points.

4. What is the significance of a function being analytic or entire?

Analytic and entire functions have many important applications in mathematics and physics. They are used to model various phenomena and are essential in solving complex problems involving calculus and differential equations.

5. How can I check if a function is entire?

To check if a function is entire, you must first check if it is analytic. If it is analytic and defined on the entire complex plane, then it is considered to be an entire function. This can be verified by checking if the function satisfies Cauchy-Riemann equations, which are necessary conditions for a function to be analytic.

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