MATH 185 - Introduction to Complex Variables

Instructor: Roberto De Leo.     Term: Fall 2020.

Gauss
Riemann

When & Where: MWF 2-3pm on Blackboard Collaborate Ultra

Email: roberto DOT deleo AT howard DOT edu

Textbook

M. Beck, G. Marchesi, D. Pixton, L. Sabalka, A First Course in Complex Analysis

Other Texts

Grades policy

Grades will be evaluated on the following bases:
  1. (Almost) weekly homework: 30%;
  2. Two take-home midterms: 2x20%;
  3. Final exam: 30%.
Based on the total, you will get the following letter: A (90-100%), B (80-89%), C (70-79%), D (60-69%), F (0-59%).

Collaboration

Especially with online classes, teamwork is very important and will give you the occasion to interacct with your classmates. You are encouraged in general to work with study partners and also to collaborate on homework. On the other side, you must write your solutions yourself, in your own words, and you must list all collaborators and outside sources of information.
It is a serious violation of academic integrity to copy an answer without attribution.

Academic Code of Student Conduct

(please see Howard University handbook) No copying, unauthorized use of calculators, books, or other materials, or changing of answers or other academic dishonesty will be tolerated. Cheating will not be tolerated. Anyone caught cheating will receive an F for the course and may be expelled from the university.

Grievance Procedure

If you have any problems with the policies or rules of this course, discuss your concerns with your instructor. If you are still unable to come to a satisfactory arrangement, you may contact the Director of Undergraduate Studies, Dr. Jill McGowan, and, if still unsatisfied, the Chair of the Department, Dr. Bourama Toni.

Americans with Disabilities Act

Howard University is committed to providing an educational environment that is accessible to all students. In accordance with this policy, students in need of accommodations due to a disability should contact the Office of the Dean for Special Student Services (202-238-2420, bwilliams@howard.edu) for verification and determination of reasonable accommodations as soon as possible after admission and at the beginning of each semester as needed.

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Lectures plan:

WeekContentTopics
1 Chapter 1 Complex numbers.
2 Chapter 2 Continuity, differentiability and holomorphicity.
3 3.1--3.3 Examples of functions 1.
4 3.3--3.5 Examples of funcitons 2.
5 4.1, 4.2 Integration 1.
6 4.3, 4.4 Integration 2.
7 Chapter 5 Applications of Cauchy's theorem.
8 Chapter 6 Harmonic functions.
9 7.1, 7.2 Sequences and series
10 7.3, 7.4 Sequences and series of functions.
11 Chapter 8 Taylor and Laurent series .
12 Chapter 9 Isolated singularities and the resideu theorem.
13 Chapter 10 Discrete applications of the residue theorem.
14 Review.

Lectures log

WeekDaySectionsTopicsHomework
124 Aug1.1Complex numbers.
26 Aug1.2Cartesian and polar representations of complex numbers.1.1,1.2,1.4(a-c),1.5(a-b)
28 Aug1.3, 1.4Geometric properties of complex numbers. Basic topological definitions.1.9, 1.10, 1.13, 1.19, 1.20, 1.29
231 Aug1.4, 2.1Planar topology. Limits.2.3
2 Sep2.1, 2.2Continuity. Differentiability and Holomorphicity.2.6, 2.15, 2.17
4 SepUniversity closed
37 SepLabour Day.
9 Sep2.3Cauchy-Riemann equations.2.20, 2.23
11 Sep2.3,2.4Harmonic Functions, Constant Functions2.21, 2.29
414 Sep3.1Mobius transformations3.5
16 Sep3.2Cross ratio and the Riemann sphere3.14, 3.19
18 Sep3.4Exponential and trigonometric functions3.31, 3.52
521 Sep3.5, 4.1Complex logarithm and exponential. Integration.3.31, 4.7
23 Sep4.2, 4.3Antiderivatives. Homotopies. Cauchy's Theorem.4.3, 4.5, 4.11, 4.15, 4.29, 4.30
25 Sep4.3Cauchy's Theorem.4.37
628 Sep4.4Cauchy's integral formula.4.34, 4.39
30 Sep5.1, 5.2For complex functions, C1 implies smooth. Morera's Theorem.5.3,5.17,5.18
2 Oct5.3The Fundamental Theorem of Algebra. Entire holomorphic functions are all constant.Extra Credit: 5.13
75 Oct5.3, 6.1Evaluating real integrals via complex ones. Harmonic functions.5.20, 6.1
7 Oct6.2Harmonic functions, Mean value theorem.6.8
9 Oct6.2, 7.1Maximum/minimum principle. Converging sequences.6.11
812 Oct7.1Sequences and Completeness.7.2, 7.15
14 Oct7.2Series. Absolute convergence.7.18
16 Oct7.2, 7.3Series convergence. Series of functions. Pointwise and uniform convergence.7.21
919 Oct7.3Exchanging derivative with infinite sign symbols.7.27
21 Oct7.4Region of convergence of power series7.34
23 Oct8.1Holomorphic functions and Power series8.3
1026 OctCanceled for bad BB Ultra connectivity.
28 Oct8.1Holomorphic functions and Power series8.9
30 Oct8.2Classification of zeros.
112 Nov8.2Identity Principle
4 Nov8.3Maximum modulus Theorem
6 Nov8.3Laurent series8.34, 8.36
129 Nov9.1Classification of singularities9.1, 9.3, 9.4
11 NovVeteran's Day
13 Nov9.2Essential singularities. Residues.9.8b, 9.8e, 9.17
1316 Nov9.3Argument principle and Rouch\'e's Theorem
18 NovInfinite sums. Binomial coefficients.
20 Nov9.2Fibonacci numbers. Coin-exchange problem. Dedekind sums.