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 Apr 24 comment Is an empty parenthesis a valid mathematical expression? ^- of course there are no values of type Nothing, but expressions can have that type. There's also scala.Null, which is the type of the null expression. Apr 24 comment Is an empty parenthesis a valid mathematical expression? Jacob: You're misunderstanding Scalas Nothing type; Nothing is a subtype of every other type, not the other way round. So a value of type Nothing can be assigned to a variable of any other type, i.e. val x: Int = ??? (??? is a predefined method of type Nothing in scala.Predef. Apr 24 comment Is an empty parenthesis a valid mathematical expression? Not sure how it works with mathematical logic, but in Haskell and Scala () is simply a built-in type that is inhabited by [only, discounting bottom] the value (). Nonterminating (or otherwise erroneous, such as division by 0) expressions are denoted by the bottom value, which inhabits all types. Jun 24 comment What is the maximum of a set of random variables? @Dominik Just to make sure - a random variable is uniformly distributed in $[a,b]$ if it is linear in $[a,b]$ and constant $0$ otherwise, and $Y_i$ is still uniformly distributed in $[0,2\vartheta]$ because you just changed the slope, not the fact that it's linear in $[0,2\vartheta]$? Jun 23 comment What is the maximum of a set of random variables? I thought I had gotten it for a sec, but... why is the EV the same for $\max X_i$ and $\max Y_i$ again? Jun 23 comment What is the maximum of a set of random variables? I get it, but I can't quite imagine how you'd get the idea for this - did you start form the assumption that it's $2\theta$ and worked backwards from there? Jun 23 comment What is the maximum of a set of random variables? wikipedia said expected value and mean mean the same thing, changed it though. Jun 23 comment What is the maximum of a set of random variables? Oh. That makes sense. Not sure how to work with that, but at least I know where to start now. Nov 29 comment Proving that idempotence follows from other lattice axioms You gotta love how these things always seem so stupidly obvious once someone tells you. Jul 1 comment Solving $y'' - \frac{1}{x} y' + (1+\frac{\cot x}{x}) y = 0$ by rank reduction Thanks. As it turns out, that was my solution, I just made an error copying it over. Jul 1 comment Solving $y'' - \frac{1}{x} y' + (1+\frac{\cot x}{x}) y = 0$ by rank reduction I get $y''(x) = -\sin(x) \int_0^x u(t) dt + \cos(x) u(x) + \cos(x) u(x) + \sin(x) u'(x)$ - I have no idea where you got the '-' in front of the second cos from. $cx^2\sin x$ can't be the solution because $\sin x$ is a solution. Jun 19 comment Does a closed form sum for this fourier series exist? Yep, as it turns out my fourier series was wrong (again). It should have been $\frac{(a+b)(-1)^{n+1}}{n}$ where it says b-a in the series (I missed a '-' in the scalar product). Yeah, but I don't think I'm gonna include a closed form for the sum in my homework after all - what you just said is a little over my head, we just briefly touched fourier series in 2 or 3 classes and then went on to the next topic. Jun 19 comment Does a closed form sum for this fourier series exist? I guess that makes sense, except I have no idea how to prove these sums either. Do you happen to know what causes my problem with (a=b)? Jun 18 comment Does a closed form sum for this fourier series exist? This isn't part of the question title - but I now noticed that this doesn't work with a=b - the sum of the series would become 0. But f(x) is not constant 0 for a=b... But I don't recall having made assumptions about a and b not being equal in my calculations... Jun 18 comment Fourier-Series of a part-wise defined function? I see. Unfortunately I don't have the time to fix this before I hand it in, but it will certainly be useful in the future. Thanks. Jun 17 comment Partial Integration - Where did I go wrong? Thanks. I "fixed" the sign when I wrote this by accident (I had it right in my notes, then for some reason when I wrote it here I thought it was wrong). May 30 comment Lagrange multiplier - find minima of a function satisfying a condition Thanks. Will do. May 30 comment Lagrange multiplier - find minima of a function satisfying a condition I don't know, I am using the notation I am used to. But unless the distance happens to be 1, why would I be able to use the square of the distance rather than the distance? EDIT: Actually, that makes sense because I can just take the square root when I have the result... EDIT2: Your signs seem off though. May 6 comment WolframAlpha blows simple substitution? My derivative may be wrong - I will check that right away - but I didn't ask WolframAlpha to calculate the derivative, I asked it to calculate my formula for the derivative for a given n. May 5 comment Doubt about function value (expected undefined, but Wolframalpha says otherwise) Actually, our Prof is very thorough when it comes to those kind of things, I just wasn't sure if it was actually ok to fix the singularity in this case...