Proving the Circle Property of Infinite Sequence in Complex Analysis

In summary, the problem is to prove that the sequence a_{n}= \prod_{k}^\infty (1 + \frac{i}{k}) when n approaches infinity constitutes points on a circle with a particular finite radius. This can be done by showing that the infinite product has a finite limit and by considering the terms of the product as pairs in an infinite series. Additionally, by setting 1/k = α and considering the argument of a_{n}, it can be shown that the entire circle is covered.
  • #1
raopeng
86
0

Homework Statement


To prove that the sequence [itex]a_{n}= \prod_{k}^\infty (1 + \frac{i}{k})[/itex] when n is infinite constitutes points on a circle.

Homework Equations


Ehh no idea what equations shall be used.

The Attempt at a Solution


A friend asked me this, but I am usually engaged more with the physical aspects of Complex Analysis... so I have no idea how I should approach this question.
 
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  • #2
Well points on a circle have a particular (finite) radius.

So you need to prove your infinite product has a finite limit,
Since we are in the complex plane this will be a radius, as every point with this modulus will be included.
 
  • #3
Thank you. Yes I noticed that too, as we can extract an infinite series from it...
 
  • #4
So what happens if you write a few of the terms of the series out and multiply them in pairs?

Further hint put 1/k = α.
So the terms take the form (1+αi)
 
  • #5
Thank you for the help. Also [itex]arg a_{n} = \sum^{\inf}_{k}\frac{1}{k}[/itex] covers the entire circle.
 

1. What is complex analysis?

Complex analysis is a branch of mathematics that deals with the study of functions of complex numbers. It combines the concepts of calculus and algebra to analyze how functions behave when applied to complex numbers.

2. What are complex numbers?

Complex numbers are numbers that consist of a real part and an imaginary part. They are expressed in the form a + bi, where a and b are real numbers and i is the imaginary unit (√-1). Complex numbers are essential in complex analysis as they allow for the study of functions that are not defined over the real numbers.

3. What are some applications of complex analysis?

Complex analysis has numerous applications in various fields such as physics, engineering, and economics. It is used to solve problems involving electric circuits, fluid dynamics, and signal processing. It also plays a crucial role in the development of quantum mechanics and the study of fractals.

4. What are some key concepts in complex analysis?

Some key concepts in complex analysis include analytic functions, complex integration, and the Cauchy-Riemann equations. Analytic functions are functions that are differentiable at every point in their domain. Complex integration is the process of finding the area under a curve in the complex plane. The Cauchy-Riemann equations are a set of conditions that must be satisfied for a function to be analytic.

5. What is the importance of complex analysis?

Complex analysis is essential in understanding and solving problems that involve complex numbers. It also provides a powerful tool for the study of many mathematical and physical phenomena. Additionally, it has practical applications in various fields, making it an important area of study for scientists and mathematicians.

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