Problem 20 - Advanced Engineering Mathematics

Question

Determine the order of the poles for the given function. \(f(z)=\frac{e^{2}}{z^{2}}\)

Step-by-Step Solution

Answer

The function has a pole of order 2 at \( z = 0 \).

Step 1: Identifying the Form

First, let's identify the form of the given function. The function is \( f(z) = \frac{e^2}{z^2} \). Here, \( e^2 \) is a constant, and the denominator is \( z^2 \).

Step 2: Understanding Poles

Poles are points where the function becomes unbounded as \( z \) approaches a certain value. In this case, look at the denominator: \( z^2 \).

Step 3: Determine When the Denominator Part Becomes Zero

The denominator \( z^2 \) equals zero when \( z = 0 \), which indicates a potential pole at \( z = 0 \).

Step 4: Finding the Order of the Pole

The order of a pole is determined by the power of \( z \) in the denominator. Here, the denominator is \( z^2 \), which indicates that there is a pole of order 2 at \( z = 0 \).

Key Concepts

Poles

In complex analysis, poles are a critical concept. These are points where a complex function becomes infinitely large, or unbounded, as the variable approaches a specific value. Simply put, a pole is a type of singularity where the function's value shoots to infinity. To identify a pole, examine the denominators of rational functions. When these denominators become zero, the function may have a pole depending on the behavior of the numerator.

• Poles can often be identified by setting the denominator of a function equal to zero.
• The location where this denominator equals zero is often the pole.

Understanding poles helps predict how a function behaves near certain critical points. For instance, in the function \( f(z) = \frac{e^2}{z^2} \), the denominator \( z^2 \) indicates a potential pole since it becomes zero at \( z = 0 \). Hence, there is a pole at \( z = 0 \). This means near \( z = 0 \), the function \( f(z) \) spikes to infinity, a typical behavior around poles.

Order of a pole

The order of a pole refers to the smallest natural number that defines how quickly a function skyrockets to infinity near a pole. Specifically, it's connected to the degree of the zero in the denominator. In simpler terms, the order of a pole tells you the degree of the polynomial term that can make the denominator zero.

• A simple pole, or first-order pole, is characterized by a linear factor in the denominator such as \( z \).
• A second-order pole involves a quadratic factor, for instance, \( z^2 \). Higher order poles follow this pattern.

For \( f(z) = \frac{e^2}{z^2} \), there's a pole at \( z = 0 \). The denominator's term \( z^2 \) indicates this function has a pole of order 2. This doesn't just tell you where the pole is, but also how fast the function's value changes as it approaches the pole. This provides insight into the complexity and nature of the pole.

Complex functions

Complex functions are foundational in complex analysis. They involve functions where the variables and outputs can be complex numbers, offering a rich field of mathematical exploration. A complex number is composed of a real and an imaginary part, expanded as \( a + bi \), where \( i \) is the imaginary unit satisfying \( i^2 = -1 \).

• Complex functions can be expressed in various forms including polynomials, rational functions, and transcendental functions.
• These functions demonstrate different properties and behaviors compared to real functions.

In our example, \( f(z) = \frac{e^2}{z^2} \), the function is rational, involving division by a complex variable \( z^2 \). Such expressions allow for complex behaviors, such as poles and other singularities, to occur. Understanding complex functions involves a study of analytical properties and exploring how they behave towards their limits, zeros, and singular points such as poles. This rich area helps us model and solve real-world phenomena within physics, engineering, and beyond.