Parametrizing Complex Line Integral

In summary, the conversation discusses the correct way to evaluate \int_{\gamma} z \: dz using parametrization techniques and the definition of complex integration. The speaker also mentions another method of calculation by replacing f(z) with f(\gamma(t)). There is a confirmation that the approach is correct and the speaker wanted to make sure there were no logical errors.
  • #1
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So this is an ultra basic question, but I'm rusty with parametrization techniques and wanted to make sure I was doing this correctly. Let's say I want to evaluate [tex]\int_{\gamma} z \: dz[/tex] where [tex]\gamma : [a,b]\rightarrow \mathbb{C}[/tex] is some path of integration. Now, I figure I can parametrize the curve and apply the definition of complex integration to arrive at the following: [tex]\gamma(t) = x(t) + iy(t) \quad \text{so} \quad \int_{\gamma} z \: dz = \int_a^b \gamma(t) \gamma(t)' \: dt = \int_a^b (x(t)+iy(t))(x'(t)+iy'(t)) \: dt[/tex] and distribute from there. Again, I know this is a very basic question, and I'm pretty sure it's correct, but it's been a while so I wanted to make sure I wasn't making some silly logical error (quite possible). Thanks.
 
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  • #2
So far so good. You are following the definition. You can also calculate this way

[tex]\int_\gamma f(z)dz[/tex]

replacing [tex]f(z)[/tex] by [tex]f(\gamma(t))[/tex]
 
  • #3
Shouldn't that be from t_0 to t_1?
 

1. What is a complex line integral?

A complex line integral is a mathematical concept that involves integrating a complex-valued function over a path in the complex plane. It is similar to a regular line integral in calculus, but takes into account both real and imaginary components.

2. Why do we need to parametrize a complex line integral?

Parametrizing a complex line integral allows us to express the path of integration in terms of a parameter, such as time, which makes it easier to calculate the integral. It also allows us to integrate over more complicated paths, such as curves and loops.

3. How do you parametrize a complex line integral?

To parametrize a complex line integral, you need to express the path of integration as a function of a parameter. For example, if the path is a straight line from point A to point B, you can use the parameter t to represent different points along the line, such as (1-t)A + tB.

4. What is the difference between a closed and open path in a complex line integral?

A closed path is a path that starts and ends at the same point, whereas an open path starts and ends at different points. In a complex line integral, closed paths can have non-zero values, whereas open paths must have a zero value.

5. What are the applications of parametrizing complex line integrals?

Parametrizing complex line integrals is used in many areas of science and engineering, such as in fluid dynamics, electromagnetism, and quantum mechanics. It allows us to calculate important quantities, such as work, potential energy, and electric fields, along a path in the complex plane.

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