Table of contents | |
Cauchy’s Integral Formula | |
Cauchy’s Integral Theorem | |
Generalisation of Cauchy’s Integral Formula | |
Solved Numericals |
Simply Connected Region
A region is termed as simply connected if, for any closed curve C within the region, all points inside C are also contained within the region. This implies that the region has no holes or isolated boundary points.
If f(z) is an analytic function and its derivative f'(z) is continuous at all points within and on a simple closed curve C, then ∫c f(z) dz = 0.
If a complex function f(z) is continuous throughout the simple connected domain D and if ∫c f(z) dz = 0 for every closed contour c in D, then f(z) will be an analytic function in D.
This theorem is also known as Morera’s theorem.
Q2. What is the value of , where C is the circle |z| = 1 is with positive orientation.
Solution: Given,
C is the circle |z| = 1 is with positive orientation
Let f(z) =
Putting 2z2 - 5z + 2 = 0
⇒ 2z2 - 4z - z + 2 = 0
⇒ 2z(z - 2) - 1(z - 2) = 0
⇒ (z - 2)(2z - 1) = 0
Now z =
∴ The value of the given integral is 2π/3.
Q3. The value of is where C is a circle |z| = 1,
Solution: Given,
C is a circle, lzl=1
Let f(z) =
Putting z(z2 + 9) = 0
⇒ z = 0, 3i, - 3i
Now, z = 0 lies inside C.
∴ The value of given integral is
Q4. Let γ be the positively oriented circle in the complex plane given by {z ∈ ℂ: |z – 1| = 1}. Then equals:
Solution: Given,
Let γ be the positively oriented circle in the complex plane given by {z ∈ ℂ: |z – 1| = 1}. Then
Cauchy Integral Formula -
Let f(z) be analytic in a region D and let C be a closed curve in D. If a is any point in D, then
here is a winding number. The winding number measures the number of times a path (counter-clockwise) winds around a point.
We have γ = {z ∈ ℂ: |z – 1| = 1}.
Now using Cauchy Integral formula we get -
53 videos|108 docs|63 tests
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1. What is Cauchy’s Integral Formula? |
2. How is Cauchy’s Integral Formula different from Cauchy’s Integral Theorem? |
3. What is the significance of Cauchy’s Integral Formula in Mechanical Engineering? |
4. How is Cauchy’s Integral Formula applied in real-world engineering problems? |
5. What are some common misconceptions about Cauchy’s Integral Formula and Theorem? |
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