Complex Variables - Spring 2020
CHANGES DUE TO THE MOVE TO ONLINE FOR THE COVID-19 CORONAVIRUS SITUATION
ARE AT THE BOTTOM OF THIS PAGE AND APPEAR IN GREEN

Carl F. Gauss, 1777-1855

Augustin L. Cauchy, 1789-1857

Georg F. B. Riemann, 1826-1866
Click on the photos to be taken to a biography presented by the MacTutor History of Mathematics Archive.


The Spring 2020 Complex Variables class.

COURSE NUMBER: MATH 5337
TIME: 12:45-2:05 TR; PLACE: Gilbreath 106 CALL# 12667
INSTRUCTOR: Robert "Dr. Bob" Gardner; OFFICE: Room 308F of Gilbreath Hall
OFFICE HOURS: 3:35-4:00 TR and by appointment; PHONE: 439-6979 (Math Office 439-4349)

E-MAIL: gardnerr@etsu.edu
WEBPAGE: www.etsu.edu/math/gardner/gardner.htm.

TEXT: Complex Variables and Applications, 8th Edition, by James Ward Brown and Ruel V. Churchill (McGraw-Hill, 2009). A 9th edition of the book is now in print and that is also an acceptable text (as are other editions of the book; the class notes are based on the 8th edition, though).

PREREQUISITE: The catalog states that Calculus 2 (MATH 1920) and Linear Algebra (MATH 2010) are the prerequisites, but some knowledge of Calculus 3 (MATH 2110) would be useful, in particular the ideas of a function of two variables and partial derivatives.

MY ABSENCE: I will have surgery in early March and will miss 2 or 3 weeks of class. In my absence, Dr. Rodney Keaton will be giving the lectures. He will follow the same format (and posted notes) as I do. I will be assigning and grading homework during this time.

DESIRE2LEARN: I will not rely on the Desire2Learn ("D2L") website. Instead, I will simply post all material directly on the internet. However, I will post your grades on D2L.

CLASS NOTES: We will use projected digital notes for the presentation of definitions, examples, and proofs of some theorems. The white board will be used for marginal notes and additional examples and explanation. Copies of the notes are online. It is strongly recommended that you get printed copies of the overheads before the material is covered in class. This will save you from writing down most notes in class and you can concentrate on listening and supplementing the notes and examples with comments which you find relevant. You should read the online notes to be covered in class before each class (we will not have class time to cover everything in the notes; they are very thorough). Try to understand the examples and the meanings of the definitions. You should also read each relevant section of the book, paying particular attention to examples.

ABOUT THE COURSE: Complex analysis is basically the study of analytic functions. As we will see, a function of a complex variable is often much better behaved than a function of a real variable! We will introduce the complex numbers as an extension of the real numbers. We explore the complex plane and give a geometric interpretation of results whenever possible. Analytic functions are defined, differentiated, and integrated. We'll extend several familiar functions (such as logarithms, exponentials, and trig functions) from the real to the complex setting. We'll prove the Fundamental Theorem of Algebra and the Maximum Modulus Theorem. If time permits, I will discuss some of my research results which are related to topics in the class. We may have the opportunity to briefly explore applications.

OUTLINE: Our tentative outline is:
Chapter 1. Complex Numbers: Algebra, modulus, conjugates, exponential form, argument, products and quotients, roots, topology of the complex plane.
Chapter 2. Analytic Functions: Functions, mappings, limits, limits involving infinity, continuity, derivatives, Cauchy-Riemann Equations, polar cordinates, analytic functions, harmonic functions, reflection principle.
Chapter 3. Elementary Functions. Exponential function, logarithm function, branches of the logarithm, complex exponents, trigonometric functions, hyperbolic functions, inverse trig functions.
Chapter 4. Integrals. Derivatives of functions w(t), definite integrals of w(t), contour integrals, branch cuts, moduli of integrals, antiderivatives, Cauchy-Goursat Theorem, simply/mulitply connected domains, the Cauchy Integral Formula, Liouville's Theorem and the Fundamental Theorem of Algebra, Maximum Modulus Theorem, Applications of the Maximum Modulus Theorem to polynomials.
Chapter 5. Series. Convergence of sequences and series, Taylor series, Laurent series, absolute and uniform convergence, continuity/integration/differentiaion of power series.
Chapter 6. Residues and Poles. Isolated singular points, residues, Cauchy's Residue Theorem, residues at infinity, residues of poles, zeros of analytic function, poles.

GRADING: Your grade will be determined by the average on a midterm (M), an optional final (F), and homework (HW). Your average is determined by whichever of the following is best:

AVERAGE = (M + F + 2HW)/4, AVERAGE = (M + HW)/2, or AVERAGE = (M + 3HW)/4.
Grades will be assigned based on a 10 point scale with "plus" and "minus" grades being assigned on a 3 point subscale (for example, a 90, 91, 92 is an A-).

TESTS AND HOMEWORK: The final will not be comprehensive. Homework will be assigned and collected at roughly one week intervals. The homework problems will be almost exclusively from the text book. As members of the graduate class, you will be given extra problems that are not required of the undergraduate students in the corresponding section of undergraduate Complex Variables (MATH 4337). YOU MUST SHOW ALL DETAILS ON THE HOMEWORK PROBLEMS!!! Justify every step and claim you make - this is how you convince me that you know what you are doing. You may find some answers online, but these rarely sufficiently justify all steps and are unacceptable as homework solutions.

ACADEMIC MISCONDUCT: While I suspect that you may work with each other on the homework problems (in fact, I encourage you to), I expect that the work you turn in is your own and that you understand it. Some of the homework problems are fairly standard for this class, and you may find proofs online or in an online version of the solutions manual. The online proofs may not be done with the notation, definitions, and specific methods which we are developing and, therefore, are not acceptable for this class. If I get homework from two (or more) of you that is virtually identical, then neither of you will get any credit. If you copy homework solutions from an online source, then you will get no credit. These are examples of plagiarism and I will have to act on this as spelled out on ETSU's "Academic Integrity @ ETSU" webpage (last accessed 5/16/2018). To avoid this, do not copy homework and turn it in as your own!!! Even if you collaborate with someone, if you write the homework problems out in such a way that you understand all of the little steps and details, then it will be unique and your own work. If your homework is identical to one of your classmates, with the exception of using different symbols/variables and changing "hence" to "therefore," then we have a problem! If you copy a solution from a solution manual or from a website, then we have a problem! I will not hesitate to charge you with academic misconduct under these conditions.

SUPPLEMENTAL REFERENCES:

SYLLABUS ATTACHMENT: You can find an on-line version of the university's syllabus attachment (which contains general information concerning advisement, honor codes, dropping, etc.; last accessed 9/14/2019).

IMPORTANT DATES: (see the official ETSU calendar for more details; accessed 9/14/2019):

ASSIGNMENTS: The following homework and due dates apply. The problem numbers are based on the 9th edition of Complex Variables and Applications.
Sections
Problems
Solutions
Due Date
Points
1.2. Basic Algebraic Properties
1.3. Further Properties
1.4. Vectors and Moduli
1.2.3, 1.2.8a, 1.2.8b
1.3.5, 1.3.8
1.5.8
Solutions
Tuesday, January 28
5 + 5 + 5 + 5 + 5 + 5 = 30
1.5. Complex Conjugates
1.6. Exponential Form
1.7. Products and Powers in Exponential Form
1.8. Arguments of Products and Quotients
1.6.7, 1.6.15ab, 1.6.15c,
1.9.2b, 1.9.6
Solutions
Tuesday, February 4
5 + 5 + 5 + 5 + 5 = 25
1.8. Arguments of Products and Quotients
1.9. Roots of Complex Numbers
1.10. Examples
1.11. Regions in the Complex Plane
1.9.5b,
1.11.1b, 1.11.8a,
1.12.8, 1.12.9
Solutions
Tuesday, February 11
5 + 5 + 5 + 5 + 5 = 25
2.12. Functions of a Complex Variable
2.13. Mappings
2.14.2, 2.14.4, 2.14.5, 2.14.6, 2.14.8
Solutions
Tuesday, February 18
5 + 5 + 5 + 5 + 5 = 25
2.15. Limits
2.18.2a, 2.18.2b, 2.18.5b, 2.18.6, 2.18.9
Solutions
Tuesday, February 25
5 + 5 + 5 + 5 + 5 = 25
2.17. Limits Involving the Point at Infinity
2.18. Continuity
2.18.10(a,b,c), 2.18.13
2.20.3(a,b), 2.20.4, 2.20.6(b) BONUS: 2.20.3(a')
Solutions
Tuesday, March 3
5 + 5 + 5 + 5 + 5 + (5) = 25 + (5)
2.26. Harmonic Functions
2.27. Uniquely Determined Analytic Functions
2.28. Reflection Principle
2.27.1, 9.115.1(a), 9.115.3
2.29.1
2.29.4
Solutions
Thursday, April 2
5 + 5 + 5 + 5 + 5 = 25
3.29. The Exponential Function
3.30. The Logarithm Function
3.31. Branches and Derivatives of Logarithms
3.30.3, 3.30.12, 3.30.13, 3.33.3, 3.33.10(a)
Solutions
Thursday, April 9
5 + 5 + 5 + 5 + 5 = 25
3.34. Some Identities Involving Logarithms
3.36. Examples
4.42. Definite Integrals of Functions w(t)
3.34.3, 3.36.2(b), 3.36.5, 4.42.2(d), 4.42.4
Solutions
Thursday, April 16
5 + 5 + 5 + 5 + 5 = 25
4.43. Contours
4.46. Examples Involving Branch Cuts
4.43.1(b), 4.43.6
4.46.7, 4.46.11(b), 4.46.13
Solutions
Thursday, April 23
5 + 5 + 5 + 5 + 5 = 25
4.47. Upper Bounds for Moduli of Contour Integrals
4.53. Multiply Connected Domains
4.57. Some Consequences of the Extension
4.47.5, 4.49.4
4.53.2(b)
4.57.1(a), 4.57.1(e)
Solutions
Thursday, April 30
5 + 5 + 5 + 5 + 5 = 25
TOTAL
-
-
-
280 + (5)
The numbers in parentheses represent bonus problems.


TRANSITION TO ONLINE

Effective March 23, all ETSU classes will be taught online-only due to the Covid-19 coronavirus situation. The remaining test will be given through D2L. Notes will remain online as usual, but videos will be posted of me presenting the notes. Class will continued to "meet" through Zoom at the usual time and we will make the best of it. You should make sure that you have signed into Zoom (using the same username and password you use for your e-mail); you will receive e-mail invitations to the "meetings" that will replace regular class meetings. You can access Zoom through D2L; we are likely to rely on D2L much more than originally planned. Details will follow as things evolve.

Links to videos of the lectures on the sections (and links to class notes and supplements) are given here:

SECTION
ONLINE NOTES
ONLINE SUPPLEMENTS
LINKS TO VIDEOS
2.26. Harmonic Functions
2.26 Class Notes
2.26 Beamer Presentation
2.26 Print Version of Beamer Presentation
2.26 Video Lecture 1 (10:30)
2.26 Video Lecture 2 (15:29)
2.28. Reflection Principle
2.28 Class Notes
2.28 Beamer Presentation
2.28 Print Version of Beamer Presentation
2.28 Video Lecture (7:08)
3.29. The Exponential Function
3.29 Class Notes
3.29 Beamer Presentation
3.29 Print Version of Beamer Presentation
3.29 Video Lecture (13:52)
3.30. The Logarithm Function
3.30 Class Notes
-
3.30 Video Lecture (12:53)
3.31. Branches and Derivatives of Logarithms
3.31 Class Notes
-
3.31 Video Lecture (12:16)
3.32. Some Identities Involving Logarithms
3.32 Class Notes
3.32 Beamer Presentation
3.32 Print Version of Beamer Presentation
3.32 Video Lecture (16:37)
3.33. Complex Exponents
3.33 Class Notes
3.33 Beamer Presentation
3.33 Print Version of Beamer Presentation
3.33 Video Lecture (23:10)
3.34. Trigonometric Functions
3.34 Class Notes
3.34 Beamer Presentation
3.34 Print Version of Beamer Presentation
3.34 Video Lecture (26:23)
4.37. Derivatives of Functions w(t)
4.37 Class Notes
-
4.37 Video Lecture (13:52)
4.38. Definite Integrals of Functions w(t)
4.38 Class Notes
-
4.38 Video Lecture (10:52)
4.39. Contours
4.39 Class Notes
-
4.39 Video Lecture (22:04)
4.40. Contour Integrals
4.40 Class Notes
-
4.40 Video Lecture (11:15)
4.41. Some Examples
4.41 Class Notes
-
4.41 Video Lecture (25:43)
4.42. Examples with Branch Cuts
4.42 Class Notes
-
4.42 Video Lecture (23:59)
4.43. Upper Bounds for Moduli of Contour Integrals
4.43 Class Notes
4.43 Beamer Presentation
4.43 Print Version of Beamer Presentation
4.43 Video Lecture Part 1 (16:24)
4.43 Video Lecture Part 2 (6:59)
4.44. Antiderivatives
4.44 Class Notes
-
4.44 Video Lecture (30:52)
4.46. Cauchy-Goursat Theorem
4.46 Class Notes
-
4.46 Video Lecture (22:48)
4.48. Simply Connected Domains
4.48 Class Notes
-
4.48 Video Lecture (13:53)
4.49. Multiply Connected Domains
4.49 Class Notes
4.49 Beamer Presentation
4.49 Print Version of Beamer Presentation
4.49 Video Lecture (27:51)
4.50. Cauchy Integral Formula
4.50 Class Notes
4.50 Beamer Presentation
4.50 Print Version of Beamer Presentation
4.50 Video Lecture (16:06)
4.51. An Extension of the Cauchy Integral Formula
4.51 Class Notes
4.51 Beamer Presentation
4.51 Print Version of Beamer Presentation
4.51 Video Lecture Part 1 (8:52)
4.51 Video Lecture Part 2 (8:53)
4.52. Some Consequences of the Extension
4.52 Class Notes
4.52 Beamer Presentation
4.52 Print Version of Beamer Presentation
4.52 Video Lecture (18:17)
4.53. Liouville's Theorem and the Fundamental Theorem of Algebra
4.53 Class Notes
4.53 Beamer Presentation
4.53 Print Version of Beamer Presentation
4.53 Video Lecture (31:09)
4.54. Maximum Modulus Principle
4.54 Class Notes
4.54 Beamer Presentation
4.54 Print Version of Beamer Presentation
4.54 Video Lecture (46:53)

Links to videos of "in-class" lectures are given here:

DATE
SECTIONS DISCUSSED
LINKS TO VIDEOS
Tuesday, March 24
2.26. Harmonic Functions
2.27. Uniquely Determined Analytic Functions
2.28. Reflection Principle
Video of March 24 Class (55:59) [Inactive Link]
Thursday, March 26
3.29. The Exponential Function
3.30. The Logarithm Function
3.31. Branches and Derivatives of Logarithms
Video of March 26 Class (1:15:48) [Inactive Link]
Tuesday, March 31
3.32. Some Identities Involving Logarithms
3.33. Complex Exponents
3.34. Trigonometric Functions
March 31 Homework 7 Hints (12:36, on YouTube)
Internet Failure During Class, no class video
Thursday, April 2
4.37. Derivatives of Functions w(t)
4.38. Definite Integrals of Functions w(t)
Video of April 2 Class (1:09:47) [Inactive Link]
Tuesday, April 7
4.39. Contour
4.40. Contour Integrals
4.41. Some Examples
Homework 8 Hints (8:26, on YouTube)
Video of April 7 Class (1:14:40) [Inactive Link]
Thursday, April 9
4.42. Examples with Branch Cuts
4.43. Upper Bounds for Moduli of Contour Integrals
Video of April 9 Class (1:26:16) [Inactive Link]
Tuesday, April 14
4.44. Antiderivatives
4.46. Cauchy-Goursat Theorem
Homework 9 Hints (7:51, on YouTube)
Video of April 14 Class (1:12:43) [Inactive Link]
Thursday, April 16
4.48. Simply Connected Domains
4.49. Multiply Connected Domains
4.50. Cauchy Integral Formula
Video of April 16 Class (1:18:04) [Inactive Link]
Tuesday, April 21
4.50. Cauchy Integral Formula
4.51. An Extension of the Cauchy Integral Formula
4.52. Some Consequences of the Extension
Homework Hints (9:54, on YouTube)
Video of April 21 Class (1:15:14) [Inactive Link]
Thursday, April 23
4.53. Liouville's Theorem and the Fundamental Theorem of Algebra
Video of April 23 Class (1:21:15) [Inactive Link]
Tuesday, April 28
4.54. Maximum Modulus Principle
Homework Hints (13:16, on YouTube)
Video of April 28 Class [Inactive Link]
Thursday, April 30
Supplement. Applications of the Maximum Modulus Theorem to Polynomials
Video of April 30 Class (1:10:22) [Inactive Link]
Unless indicated otherwise, videos were recorded in Zoom (in which case they will be automatically deleted after 1 year).


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Last updated: May 29, 2020.