# Search results

1. ### Python [python] Bitwise Operations

I'm playing around in Python at the moment, and I came across an exercise to perform bitwise operations manually (without the built in & | ^ ~ operators). I understand the operations on paper, and I have a function here that performs them (& in this case, the others are similar): def...
2. ### Distance of a point on the earth from the sun

A question was posed that I decided to have a crack at, and I want to check my understanding. This isn't homework by the way, just trivia. Also the thread title is not really correct but I didn't want to complicate things! Here's the question: What is the relative difference in the distance...
3. ### Math Advice on alternative career paths with B. Comp Sci (Maths)

I've just finished my undergraduate degree, and am enjoying a few weeks of complete bliss with no assignment deadlines! I've been thinking a lot about my future career, and I was hoping to gain some insight and advice on possible directions. I have a B. Comp Sci with a major in Computational...
4. ### FDM Heat Equation FTCS Scheme with NBC

Homework Statement I have a quiz question that I'm struggling with. We've been working on using a FTCS scheme with two Essential Boundary Conditions, and now I have a problem with one EBC (ie static) and a Natural Boundary Condition (ie a derivative). The condensed problem statement: u_{t} =...
5. ### Classification of PDEs

Homework Statement I'm doing a course on numerical solutions of PDE and I am waaaay out of my depth, having not covered differential equations previously. I spoke to my lecturer about this and he said I would be fine as the course is on FDM/FEM and not analytic solutions but this is week 4 and...
6. ### Finite Difference Method - clarification of a term

Homework Statement I'm doing a class on Numerical Solutions of DE and I have my first assignment. The problem is stated: Consider the following second order boundary value problem: \epsilon \frac{d^{2}y}{dx^{2}} + \frac{1}{2+x-x^{2}} \frac{dy}{dx}-\frac{2}{1+x}y = 4sin(3x), y(0) = 2, y(2) =...
7. ### Which method of integration for sin^2(x) dx

During maths class last semester this integral came up in the course of discussion and my lecturer gave a quick outline of how to solve it but I didn't grasp it at the time and we moved on. I'd like to know how to do it though! The integral is: \int sin^{2}(x) The next step was: \int...
8. ### Bayes Theorem for coins problem

Homework Statement I have a bag of n coins, and 1 is fake - it has 2 heads. a) Determine the probability that if I flip a coin and it comes up heads, the coin is fake. b) If a coin is flipped k times and comes up heads k times, what is the probability that the coin is fake? Homework...
9. ### Linear Transformation from P2 (R) to P3 (R)

Homework Statement Let T be the linear transformation from P2 (R) to P3 (R) defined by T(f)=14\int_{0}^{x}f(t)dt + 7x.f'(x) for each f(x)=ax^{2}+bx+c Determine a basis {g1, g2, g3} for Im(T). Homework Equations as above The Attempt at a Solution I evaluated the...
10. ### Show that the set S is a subspace of R^3

Homework Statement Determine if the set is a subspace: S = {(a, b, c) 2 R3 | a − 2b = 0 and 2a + b + c = 0}; Homework Equations as above The Attempt at a Solution It is a subspace, I'm just not 100% sure how to write up the proof. So far I have this: The set is non-empty...
11. ### Scalar potential of a function F, stuck on curl(F) != 0

Homework Statement I have a function F defined in a slightly strange way, and I'm not asked to test if curl(F) == 0, but I thought I would do this as part of my working out. Lo and behold, it looks like it doesn't == 0, and this means, as far as I know, that there is no scalar potential but...
12. ### A complicated derivative using chain rule

Homework Statement I have a function z, and I need to find the derivative dz/dt "using the chain rule without substitution" Homework Equations z = x^{2}y^{3} + e^{y}\cos x x = \log(t^{2}) y = \sin(4t) The Attempt at a Solution \frac{\mathrm{d} z}{\mathrm{d} t} =...

I'm reading a binary file with fread, and I'm getting some strange results. This is from the man page: size_t fread(void *ptr, size_t size, size_t nmemb, FILE *stream); The function fread() reads nmemb elements of data, each size bytes long, from the stream pointed to by stream, storing them...
14. ### Cold War books / movies

I'd like some new material to devour, and I have an interest in this era for some reason, particularly the spy stuff (!) but also the space race, and other associated topics. I don't mind if it's fact or fiction really, it's not an academic pursuit. I'd quite like some books, so I can read them...
15. ### Linear Algebra / Vector Calc Text (for CompSci student)

I'm taking a Linear Algebra / Vector Calculus course this semester as part of a maths major for my Comp Sci undergrad. degree. We don't have a prescribed text, but I'd very much like a hard copy of something that I can reference. The course is somewhat compressed compared to what the Maths...
16. ### Age gap of two people dating

I'm going to go ahead and put this to the board, figure I might as well. I'm 30 years old, and a pretty quiet person. Friendly, polite, but stand-offish with most people. Anyway, enough with the background. There's a girl at my work who I think is great. She's gorgeous, a little reserved, and...
17. ### Stargazing Amateur Astrophotography

I saw this mentioned in a few threads, and I thought, seeing as I just inherited a 2nd hand digital camera from my dad, maybe I should give it a go. Any tips for a beginner? I guess I should get a tripod. My camera is an Olympus SP-55OUZ with manual settings and 18x optical zoom. It's a...
18. ### What has the smallest brain

At what point, or scale, do organisms/lifeforms/whatever have brains?

Homework Statement Perform file IO with 3 reader and 3 writer threads using a circular buffer. Read the (text) file in and write the same file out. The Attempt at a Solution I have an assignment that requires me to use multiple (3) threads to read data from a file, and multiple threads...
20. ### Simple exponential function exercise

Homework Statement is e^x^2 = 4 equivalent to e^x = 2 Homework Equations As above The Attempt at a Solution This is just an exercise, but I'm quite stuck as how to show this is true (or false for that matter). I thought to take the log of both sides and use the log identity to get...
21. ### Partial Derivate of multivariable cos

Homework Statement Partial derivative of R = vt cos x with respect to t Homework Equations NA The Attempt at a Solution Keeping the other variables constant, I get 'v cos x'. (t is 1) I just want to check this, because it's part of a larger problem and I feel my answer is way...
22. ### Convergence of Bisection Method

Homework Statement Show that the Bisection Method converges linearly with K = 1/2 Homework Equations Note that x(sub n) converges to the exact root r with an order of convergence p if: lim(n->oo) (|r - x(n + 1)|) / (|r - x(n)|^p) = lim(n->oo) (|e(n + 1)|) / (|e(n)|^p) = K The...
23. ### How important is an internship, or vacation work for an aspiring programmer

I'm 2nd year of 3 into my CompSci degree, and just (!) starting to think about employment after I graduate. I've been ... lost ... shall we say for a good long time, back at uni after a long break, enjoying it, working hard etc ... but I have no idea what I want to do when I finish, except that...
24. ### Small Talk

I'd like to improve my conversational skills - I'm kind of anti-social, and it's dawning on me that I am going to die alone if I don't start talking to people. I've reached this strange place in my life, and I don't quite know how I got here. I used to be, well, a bit shy but I could start a...