Announcement about course
grade:
After curve, the grade percentage breakdown is as follows:
F 52D, 56D+,
60C, 64C, 68C+, 72B,76B, 80B+, 84A, 88A, 94A+
I have spent hours to find every possible grade lifts following
the criteria: within 1% to the next level AND have shown
improvements over the semester (or have been active in
class). I have also taken into account your extra credits
from homework if there is any.
The grades have been submitted to SIS. I can not change it.
If you are sure that I made a mistake in your grade assignment,
please email me with your section number and all your scores. We
will go to SIS to make the change. This process will be recorded
by paperwork. The JHU Ethics Statement below applies.
If you do not get the grade you wished:
I am sorry that your grade does not work for you. You may consider
retaking the course in summer or other semesters. When you take
the course again, please do talk with your teacher (and TA) about
your situation early. More importantly, please do put a reasonable
amount of efforts in the course. Your grade is
determined by you, not by us. As teacher, following the
JHU policies and ethics, we are here to help you to learn and to
earn a better grade. But in the end it is your efforts that
determines the grade.
Any efforts asking for a better grade than reasonable will be
ignored. Your grade is determined by your efforts, not by me or
your TA. I can not arbitrarily change your grade. We must follow
the policies. The JHU ethic statement applies to you, as well as
me and your TA. Please do not keep on contacting me for an
unreasonable grade, such an action is disrespectful and is
unethical.
Instructor: Fei Lu
Office: Krieger 301
Office Hours: MF 1112 + after classes in classrooms:
12:501:15, and 2:202:50
Website: http://math.jhu.edu/~feilu/18Spring/DE302.html
Email: feilu##
(Here and in the following, ## = @math.jhu.edu)
Lectures and sections:
Lectures 
Recitation
Sections 

Sec # 
Time 
Place 
TA 
Office hr 
Email, office 

MWF 12:00  12:50PM Levering Arellano 
1 
T 1:302:20 
Maryland 309 
Jeffrey Marino 
Th 12 
jmarino9##, Krieger 211 

2 
T 3:003:50 
Maryland 217  Patrick Martin 
mmart152##, Krieger 211 

3 
Th 3:003:50  Gilman 55 
Emily Stoll 
T11:151:15 
estoll2@jhu.edu, Krieger 207 

7 
Th 4:305:20 
Maryland 217  Emily Stoll  T11:151:15  estoll2@jhu.edu  
MWF 1:302:20 PM Maryland 110 
4 
T 4:305:20  Maryland 217  Cheng Zhang 
W34 
czhang67##, Krieger 211 

5 
Th 1:302:20 
Gilman 17 
Xiaoqi Huang 
Th 45 
xhuang49##, Krieger 200 

6 
Th 3:003:50  Hodson 313 
Xiaoqi Huang 
Th 45  xhuang49##, Krieger 200 
Textbook: Elementary Differential Equations and Boundary
Value Problems (10th Edition or later) William E. Boyce and
Richard C. DiPrima.
We will basically cover the material detailed in the official 110.302
Differential Equations Course Syllabus. I may slightly alter
this material depending on the progress of the class, and I
strongly recommend to take notes in class.
Grade Policy: There will be weekly homework sets (10%),
two inlecture midterm exams (50%) and a final (40%). The
schedule of these exams is given with the homework problems below.
There will be no makeups on homework or exams.
Academic Support: Besides attending the lectures and
the recitation sections I encourage you to use the following
opportunities for additional academic support:
Special Aid: Students with disabilities who may need special arrangements within this course must first register with the Office of Academic Advising. I will need to have received confirmation from the Office of Academic Advising. To arrange for testing accommodations please remind me at least 7 days before each of the midterms or final exam by email.
JHU Ethics Statement: The strength of the university
depends on academic and personal integrity. In this course, you
must be honest and truthful. Cheating is wrong. Cheating hurts our
community by undermining academic integrity, creating mistrust,
and fostering unfair competition. The university will punish
cheaters with failure on an assignment, failure in a course,
permanent transcript notation, suspension, and/or expulsion.
Offenses may be reported to medical, law, or other professional or
graduate schools when a cheater applies.
Violations can include cheating on exams, plagiarism, reuse of assignments without permission, improper use of the internet and electronic devices, unauthorized collaboration, alteration of graded assignments, forgery and falsification, lying, facilitating academic dishonesty, and unfair competition. Ignorance of these rules is not an excuse.
In this course, as in many math courses, working in groups to study particular problems and discuss theory is strongly encouraged. Your ability to talk mathematics is of particular importance to your general understanding of mathematics. You should collaborate with other students in this course on the general construction of homework assignment problems. However, you must write up the solutions to these homework problems individually and separately. If there is any question as to what this statement means, please ask the instructor.
Week 
Topic and Sections 
Homework 
Due 
Other 
Additional Exe(to PILOT) 
1/292/2 1/29 1/31 2/2 
1.1 Basic Models:
Direction Fields 1.2 Solutions to Some ODEs 1.3 Classification of ODEs 2.1 Linear Equations 
1.1: 6, 14, 1520 1.2: 3, 8, 13, 15 1.3: 2,4,6,9 2.1: 10,20,21,28,30,35 
Friday 2/9 Solution by Patrick Martin 
Tools to plot slope fields: GeoGebra Bluffton U Walfram 
1.1:
25 1.2: 9,16 [5,6] 1.3: 14 2.1: 22. 29, 34 [37,38] *[] is more challenging. 
2/52/9 2/5 2/7 2/9 
2.2 Separable Equations 2.3 Modeling with 1st Order ODEs 2.4 Linear/Nonlinear Differences 2.5 Autonomous Equations 
2.2: 2,5,14,22,25,29 2.3: 11 2.4: 4,5,14,15,26,27 2.5: 3,4,7,9,14,16,17 
2/16  Friday 2/9: last day to add courses 
2.2: 11,21 [30,32] 2.4: 25 [32] 2.5: 2, 13 
2/122/26 2/12 2/14 2/16 
2.5 Bifurcation Diagrams 2.6 Exact Equations 3.1 Homogeneous Equations 
2.5: 26,27 2.6: 2,6,8,12,14,16 3.1: 5,7,14,17,20,21 
2/23  2.6: 5, 15, 17 3.1:18, 22 

2/192/23 2/19 2/21 2/23 
3.1 Homogeneous Equations 3.2 The Wronskian 2.8 Existence and Uniqueness 
3.1: 24, 26 3.2: 1,4,8, 14,18,26,28,31, 33,37 (2.8: read 13,14) 
3/2 
3.1: 25 3.2: 15,21,24,32 

2/263/2 2/26 2/28 3/2 
3.3 Char. Eqn.
Roots: Complex 3.4 Char. Eqn. Roots: Repeated 3.5 Undetermined Coefficients 
3.3: 10, 14,19,26 3.4: 4,8,18,24,27 3.5: 3,10,12,14,17,30 
3/9 
Notice: Exam 1 Sample 
3.3: 17 3.4: 10,25 3.5: 9 
3/53/9 3/7 3/9 
Exam 1 on Monday: Covers to
3.4 3.6 Variation of Parameters 4.1 nth Order Linear Equations 4.2 Homogeneous Eqns 
3.6: 4,8,12,16,21,28,30 4.1: 3,8,14,18,19 4.2: 12,14,32 
3/16 
Sunday 3/11: last day to drop the course 
3.6: 19,29 4.1: 7 4.2: 31 
3/123/16 3/12 3/14 3/16 
4.3 Undetermined Coefficients 7.1 Introduction to Systems 7.2 Review of Matrices 7.3 Linear Algebraic Eqns 
4.3: 1,2 7.1: 3,6,8,15 7.2: 2,10,12,22,24 7.3: 2,7,8,15,16,17,18 
3/30 
4.3: 31 7.1: 10 7.2: 12,21 7.3: 4 

3/193/23 
Spring Vacation 

3/263/30 3/26 3/28 3/30 
7.4 First Order Linear Systems 7.5 Homogeneous Linear Systems 
7.4: 4,6 7.5: 1,4,8,9,12,16,24 
4/6 
7.4: 7 7.5: 10,15,25 

4/24/6 4/2 4/4 4/6 
7.6 Complex Eigenvalues 7.7 Fundamental Matrices 7.8 Repeated Eigenvalues 
7.6: 2,7,10,15,22 7.7: 3,4,6,7,12 7.8: 3,9,15 
4/13 
7.6: 15  do it after 4/6
lecture 
7.6: 4,21 7.7: 2,11 7.8: 2 
4/94/13 4/9 4/11 4/13 
7.8 review of Chapter 7 9.1 The Phase Plane 9.2 Autonomous Systems 
9.1: 1&6(abc), 14,18,20,21 9.2: 5,7,17,23 
4/20 
9.1: 15 9.2: 6,18 

4/164/20 4/16 4/18 4/20 
9.3 Locally Linear
Systems 9.5 PredatorPrey Equations 
9.3: 1,3,11,20,27 9.4: 3,7 
4/27 
9.320 (c):
draw a phase portrait only, discard the other parts. 
9.3: 2, 8 9.4: 6 
4/234/27 4/25 4/27 
Exam 2 on Monday:
covers to 9.4 
9.7: 2,4,9,16 6.1: 2,5,9,14,23,28 
5/4 
Sample
Exam 2 Solution
to SE2 (corrected #4) solution to E2 P4b 
9.7: 3, 10 6.1: 3,10,13,23 
4/305/4 4/30 5/2 5/4: review 
6.2 IVP Solutions 6.3 Step Functions 6.4 ODEs with Disc. Forcing Func. 
6.2: 12, 21 6.3: 13,20,21 6.4: 3(a),5(a) Practice Exam (updated) Solution (Thank Patrick Martin) [Corrected #2] 
NA 
Important: course evaluation.
*** 

5/95/17 
Final Exam Period 
Wed.
May 9th, 9am12pm Hodson 110 