What are the entire functions with bounded modulus on the complex plane?

In summary, the maximum modulus principle states that the only entire functions that are bounded are constant functions. Since |zf(z)|<=1 for all z in C, zf(z) must be constant. Therefore, the only function that satisfies this property is f(z)=0.
  • #1
g1990
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Homework Statement


Find all entire functions f(z) with the property that |zf(z)|<=1 for all z in C


Homework Equations


The maximum modulus principle says that the only functions that are entire and bounded are constant functions.


The Attempt at a Solution


I know that if f(z) is entire, then zf(z) is also entire. Thus, if it's modulus is bounded on C, then it must be constant. Thus, zf(z)=c, so that f(z)=c/z where c is a constant. But then, f is not entire. Am I doing something wrong? Or is the only function that satisfies this property zero?
 
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  • #2
That looks right to me. Only f(z)=0 works.
 

FAQ: What are the entire functions with bounded modulus on the complex plane?

What is the maximum modulus problem?

The maximum modulus problem is a mathematical concept that involves finding the maximum value of a complex-valued function over a given domain. It is often used in the study of complex analysis and has applications in various fields such as engineering, physics, and economics.

How is the maximum modulus problem solved?

The maximum modulus problem is typically solved using the Cauchy-Riemann equations and the concept of analyticity. By finding the critical points of the function and evaluating the modulus at these points, the maximum modulus can be determined.

What is the significance of the maximum modulus problem?

The maximum modulus problem has several important applications, such as in optimization and control theory. It is also a fundamental concept in the study of complex analysis and helps to understand the behavior of complex functions.

What is the difference between the maximum modulus problem and the maximum value problem?

The maximum modulus problem deals specifically with complex-valued functions, while the maximum value problem applies to real-valued functions. Additionally, the maximum modulus problem has a unique solution, while the maximum value problem can have multiple solutions.

Are there any limitations to the maximum modulus problem?

One limitation of the maximum modulus problem is that it assumes the function is analytic over the given domain. If the function is not analytic, the maximum modulus may not exist or may be difficult to determine. Additionally, the maximum modulus may not always provide the most accurate representation of the function's behavior.

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