# What is Classes: Definition and 591 Discussions

The Olympic sailing classes have been used in the sport of Sailing/Yachting during the Olympic Summer Games since 1896. Since then, 46 different classes have been used.

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1. ### C/C++ struct compared to classes

Moderator's note: thread split off from https://www.physicsforums.com/threads/why-should-the-copy-constructor-accept-its-parameter-by-reference-in-c.1049624/ That is true, but I am continually surprised and impressed about how much C++ is in C if you just know where to look, "struct" has almost...
2. ### Courses Navigating Two Math Classes and an Elective Simultaneously

This semester I am taking calculus 3 and ODE, along with an intermediate CS class and a general elective communications course. I'm wondering how difficult these two will be when taken together. I took Calc 2 the semester prior and got an A, but have never taken 2 math classes simultaneously...
3. ### Binary operation on equivalence classes

So, my approach and solution are as follows: $$[x * y] = \{ z \in M : z \sim (x * y) \}$$ Since we know that ##a * b \sim a^{\prime} * b^{\prime}## we can rewrite ##z## as ## x^{\prime} * y^{\prime} ##. Plugging this in yields:  [x * y] = \{ x^{\prime}, y^{\prime} \in M : x^{\prime} *...
4. ### Schools Taking in-person and online classes at two colleges at the same time?

I am currently in a college. And the college that I am currently at doesn't offer the class online. Can I go to a different college to take the classes online, and still be at the same college I'm at? I need the class online, it makes my school life and work life function more smoothly.

6. ### How to make progress in programming classes?

Hi everyone, Hopefully I'm writing this in the correct part of PhysicsForum. Here is my problem: I'm really struggling with my programming class (basics of python3 - loops, dictionaries, numpy). What I did this semester: 1. Participated in every class 2. Solved everything our course offered...
7. ### Physics Going back to grad school after having finished all classes

I was in graduate school for an Applied Physics PhD program for 3 years, where I got my Master's and took all the required classes for the PhD. I left because I wanted to try my hand at teaching, and I LOVED it. Now I am 34 years old, and I am wondering if there is any possibility of going back...
8. ### I Multiplication and addition definition of congruence classes

The definitions of them seem like arbitrary choices or an abuse of notation. I wonder what the reasons behind the definitions are. Thanks. PS. My instructor said such defs simplify the process of solving modular equations.
9. ### Studying Help How do I raise my GPA? I have a full schedule with hard classes

Considering I barely passed summer semester with embarassingly terrible grades (which was only 2 months long and exams are on campus and were binary multiple choice question meaning no partial grades so you either know it or you don't and there is no close in science) are as follows: Course...
10. ### Studying How to concentrate better?

Hi! I recently noticed I have really big problems concentrating when attending my college lectures (1year). Let me give an example: I come to the physics lecture and I'm totally engaged in the lecture material. But after 20min I start to lose interest and I have to physically force myself to...
11. M

### Python Classes: why do we need them?

I'm looking at a script and it begins with class Solution(object): def lengthOfLongestSubstring(self, s): but what is the point of line 1? I've tried reading, and am pretty confused. Also, what is the purpose of "self" in the function? At some point later the script writes ob1 = Solution()...
12. ### Why are structs used for linked lists and classes used for binary trees?

Why are struct use for linked list and classes used for binary tree. honestly what is the different between a class and a struct? I have a teacher one tell me that a class was a struct on steroids. but what does that really mean ?
13. ### Cheating in college classes: how common is it?

Hoping to start a discussion on a topic that seems rarely discussed here. In your direct or indirect experience, how commonly do students cheat in college classes? In what situation does cheating occur commonly? Did it occur in undergraduate or graduate school?
14. ### Other Can I Take Online Classes with a Busy Schedule?

May be a dumb question, but I know very little about online classes. My main question is, and I assume it does vary depending on a number of factors, but in general, is it possible to complete online classes while working a full time job with sometimes up to 80 hours a week or more. For...
15. ### I Determining the number of conjugacy classes in a p-group

The book I am using has a number of exercises like this: If G is a p-group, show that G cannot have exactly p+1 conjugacy classes. If G is a p-group with p+2 conjugacy classes, show that the order of G is 4. I can never solve any problem that involves connecting the number of conjugacy...
16. ### Exploring Python Special Methods & Classes

Hello Forum, In Python, methods are functions which are defined inside a class. Python has many reserved keywords and built-in functions like print(), add(), type(), etc that we commonly use even when we don't create classes, instances, etc. Whenever we use an operator (like + or - ) or a...
17. ### Looking for online/book Problems about the Python Classes

I started to learn classes in python and I am looking for problems about them. Are there any good online sites that I can find problems about them. If they also contain solutions, that would be great, but if not that is also okay. Problems can have the form like An administrator is a special...
18. ### Help in my program using Classes

Hi I am integrating my program into using different Classes. I have been trouble shooting for a while and I am stuck on this error and I don't understand the problem even reading online. I am using two Specification files with no Implementation files. I just want to make it easier with less...
19. ### C/C++ Deriving from C++ STL classes?

I'm not a newbee to C++ but I've been out of the loop for a while. I know it's discouraged, if not directly a no-go, to derive from STL classes. Something that has to do, if I remember correctly, with the STL classes having no virtual destructors. It will work in the short run but may...
20. ### Proof of Monotone Classes and Subsets in Measure Theory

My question is how to show ##\mathcal{F} \subset \sum'##. Here is my work for the problem: Proof of hint: First we'll show ##\sum## is a monotone class. Let ##(A_n)_{n\in\mathbb{N}} \subset \sum## and ##F \in \mathcal{F}##. There are two things to verify. Suppose ##(A_n) \uparrow A =...
21. ### Courses Uncertain on which classes to take next semester

I'm nearing the end of community college, 2 more semesters to go to finish up math and physics major classes. I took differential equations and physics 1 (mechanics) this semester - found ODE easy and intro mechanics challenging; I tend to do well in math classes, but am not the most talented...
22. ### Which 4 classes are the easiest?

Okay so which 4 classes would you recommend me to take? I am only wanting to teach high school astronomy LOL however, I have to pick 4 classes from here. Easiest classes would be?
23. ### I Energy-Momentum Tensor: How Much Do University Students Learn?

There are plentty of textbooks and online papers that talk about the energy momentum tensor, but they all look to me as if they're only covering the very introductory aspects of it. To put another way, it seems that there's much more to be learn. I would like to know if university physics...
24. ### Courses Amount of Classes Each Semester

Hi! I'm unsure of what major to pick as an undergrad (physics vs. quantitative biology vs. mathematics), but I'm not too worried at the moment about the major at the moment - I'll do an evaluation at the end of this semester to determine where my strengths and interests are. What I'm more...
25. ### A Differentiation Classes

I am studying Choquet-Bruhat's Introduction to General Relativity, Black Holes and Cosmology, and I don't follow the hint in Exercise I.2.1: Exercise I.2.1 Let U,V be open subsets of R^d. Prove that a C^1 diffeomorphism f:U-->V with f of class C^k is a C^k diffeomorphism. Hint: ##\partial (f...
26. ### Testing Which are the physics topic included in GRE classes?

Which are the physics topic included in GRE classes?
27. ### Do any of the higher classes require memorization?

I think the concept of memorizing (at least in the pure sciences) is not correct at all. I think it requires pure logic and skills over anything else. Memorizing is just 1 percent of the deal. I am a BSc first year student and I got an A in Zoology-I despite not having a photographic memory. I...

29. ### Taking 4 difficult ENGR related classes and working a part-time job?

I am taking next semester Differential equations, University physics 2, Electrical circuits class and lab and an Introduction to engineering course at a community college and I am planning to work part time. Is it a good idea or at least doable to do those classes and take a part-time job less...
30. ### Solid State Group theory paper suggestions for my classes

I teach group theory for physicists, and I like to teach it following some papers. In general my students work with condensed matter, so I discuss group theory following these papers: [1] Group Theory and Normal Modes, American Journal of Physics 36, 529 (1968) [2] Nonsymmorphic Symmetries and...
31. ### Other What's your note taking method in physics classes?

Upon entering my first physics class, I've noticed that taking notes is radically different than in any other class. It seems that during lecture one has two options. Option 1: Don't take very many notes at all, and instead focus on the lecture. Option 2: Take good notes, and miss what the...
32. ### Studying Good resources to help with hard physics classes?

I'm having quite a bit of difficulty in my college's intro honors, calc-based physics class. I want to find some good resources, either online or text, to assist with learning the material. The issue I'm having is that most resources I find are either not in depth enough, or they're just as...
33. ### Courses Need help deciding on one of my classes for my last semester

These are the classes I have decided so far for the next semester. Every prerequisite listed is a class I have already taken: Statistical Inference Sampling and parameter estimation, tests of hypotheses, correlation, regression, analysis of variance, sequential analysis, rank order statistics...
34. ### Studying How to study properly for physics classes

Hi, I'm starting my undergraduate physics degree this Monday and I'm trying to make up a good system of how I'm going to learn efficiently. This is what I came up with so far. The courses at my uni don't always follow a textbook, just parts of some, so I'll ask the lecturers about these and...
35. ### Programs Advice on Extra Math Classes for a Physics Degree

To preface, I'm starting my Physics degree this upcoming semester. For the past year, I've been doing all of my generals while I took care of the mathematical prerequisites for the degree (College Algebra Preparation Class, College Algebra, and Trigonometry). Now that those are complete, I can...
36. ### Schools Is this too many classes for one college semester

Fashion Art Techniques I The Science of Light and Color Introduction to the Fashion Industry History of the United States I Introductory Algebra GLBTQ Literature children's literature Foundations of Education Child Psychology and Development
37. ### Other List of Books to use for self-study before AP classes

I plan on taking a multitude of AP classes next year. I would like some books that I should buy for good study.
38. ### Schools Senior year before grad school: what classes to take?

Hi, I have one year of undergraduate classes left. I am trying to figure out how best to prepare for my applications to an AMO physics program (hopefully highly competitive). My first question is: how much importance can one class have? Maybe I am stressing too much about trying to make myself...

49. ### Courses Would taking Calc III make up for having *Zero* AP classes?

Hi PF! :') Ultimately, I've taken zero AP classes in my entire time in high school and, at first, I didn't see this as a problem. But now there are a couple of people who've told me otherwise (in terms of getting into college for undergrad). SO, if I take calc III at my local community college...
50. ### Courses Choosing classes in BSEE

Hello, I have a question for engineers, and I'm hoping they can assist me in selecting the most beneficial classes while pursuing my BSEE. First, let me give you my background in case that helps. I'm in the US, and already employed within my desired field (generally). My job title/labor...