Writing Definition and 712 Threads

Homework Statement Let f: A --> B be a function and let S, T \subseteq A and U, V \subseteq B. Give a counterexample to the statement: If f (S) \subseteq f (T); then S \subseteq T: Homework Equations The Attempt at a Solution PF: Assume f(S) \subseteq f(T). Let x \in...

I am new at the forums and still getting used to writing in Latex. I found that it is easier for me to write my LateX in this editor: http://www.codecogs.com/latex/eqneditor.php and then copy to the physics forum. So, I wanted to ask you guys, do you know any other tricks you want to...

Hi, I was just wondering if there's anyone on this forum who enjoy writing, just in general? Maybe for comics or comedy? I know there is a lot of people with strong scientific backgrounds who write for shows like The Simpsons or Futurama. For example there is Ken Keeler who has a PhD in...

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Hi, I know this isn't a technical question but I have to write a technical report based on a data acquisition program which I have created. I am a bit confused about the tenses of one section, namely 'Analysis of System operation' . Although the program has already been made, i feel that it...

I'm writing a superhero story. This fellow acquires superpowers, sort of like Superman. He has some pals that he let's in on his abilities, and of course they want him to ferry them around the world. Problem... it's impractical at jetliner speeds, eh?:confused: So I came up with this idea...

Homework Statement Given: https://www.physicsforums.com/attachments/56653, show that this can be written as: https://www.physicsforums.com/attachments/56651. Homework Equations Hint: https://www.physicsforums.com/attachments/56652 The Attempt at a Solution Quite confused by this...

Is there a general method for this? I remember in complex analysis going the other direction; that is, a function of z becoming a function of x and y. But I need to turn a complex function in a function of just z, for the purpose of integrating with respect to z. In particular, the function...

I have a C code that creates a small histogram, but I need it to rerun many many times by changing one variable that the user can input. I've NEVER used C until this week so if someone could given me an idea of how to write a script to repeat a code and save a bunch of data from it that would be...

Hi, I'm working my way through the project euler problems in c++ and I've got to one where you have to sum 100 numbers that are each 50 digits long to find the first 10 digits of the sum. Obviously I could solve it by summing each of the figits in turn then work with them to deal with...

I have a question about diffrence between ways of defining a certain plate like (3^1/2)x+y+17.3=0 to MCNP code .for example I know we can define it to MCNP with 15 p 3 2 0 6 but I couldn't understand this method 15 10 0 5 8.66 0 10 0 1

Homework Statement In electrostatics it's useful to have ##\rho (\vec x )## written with Dirac's delta so that we can know the total charge by integrating the charge distribution over a region of space. Many problems/situations deal with point charges. In Cartesian coordinates for example...

Hello all, It's quite a mouthful but I need help writing a function that will behave as follows: 1.if called with an argument which is an integer, it will return the absolute value of the input 2. if called with a real argument, it will return the number rounded to the nearest...

Do any of you look at source codes from websites, do you write source codes?

I am curious about the note taking strategies implemented by others on this board. I am referring to notes taken while reading (as opposed to notes taken during a lecture). As I progress further in my studies, I am noticing that I learn the material best when my notes become somewhat of a...

How do you start a proof for "Show 4 < 5"?

I'm waiting to hear back from grad schools, and I'm worried my writitng score on the GRE might keep me out of some schools... here is a breakdown of my scores: Verbal: 160 Quant: 159 Writing: 3.5 Physics Subject: 830 GPA: 3.92 I'm not sure why my writing score sucked so bad, but most...

Homework Statement A wave travels along a string in the positive x-direction at 27 m/s. The frequency of the wave is 46 Hz. At x = 0 and t = 0, the wave velocity is 2.6 m/s and the vertical displacement is y = 3 mm. Write the function y(x, t) for the wave. (Use the following as necessary: x...

Just something I'm a little curious to know about other physics enthusiasts. I used to just read textbooks and try keeping it in pristine condition, but in the recent year I gave into my urge to highlight and write on textbooks. Nowadays I just write, underline, and scribble whatever I want...

Hello again! I'm also interested in creating a PF interactive SciFi Madlib. What we need is a wild story with interchangeable elements for people to add their own "nouns, verbs, adjectives etc...". I can't write it, but I can make it interactive and upload it for all to enjoy!

I'm interested in creating a SciFi "choose-you-own-adventure" style story while using PF members as characters! It would be in the simple style of "story content" then choose "option 1" or "option 2" or "option 3" and repeat etc. I can't do much writing, but I can put it all together and...

Homework Statement Problem figure The rigid body assemblage shown in the figure above, has a force P(t) acting upon it (varying with time). Pick a generalized coordinate such that a single degree of freedom equation of motion can be written. There is a black, massless, rigid bar. Call this...

I'm writing a program that simulates circular "particles" in 2d space. I'm at the collision handling part. I've already corrected their positions when an overlap occurs. So, my question is, how do I determine the angle of each particle's velocity after the collision? I have the position and...

I am reading the paper http://arxiv.org/abs/hep-th/9701037. In equation (2), the author write the determinat as traces, but I don't know how to do this. I know that ##det(e^A)=e^{tr(A)}##, where ##A## is a complex matrix, and ##det(A)=e^{tr(L)}##, where ##e^L=A## and ##L## is also a complex...

Hello, I have the attached paper, and I want to write equations 4, 5 and the equation in the first line after equation 5 in MATLAB. I did it as following: Np=24; L=19; TapsL=[1 19 20]; S=length(TapsL); Index=zeros(S,1);%Tap Locations c=zeros(L+1,1); cHatMP=zeros(L+1,1)...

I'm writing something, and I need some assistance. Namely, I want it to be at least moderatly accurate to real life physics, so I would appreciate it if someone could give me an insight on how real-world physics would work in the following situations. First - what would happen if a human...

Hello, Quick question, not really homework but more of a general inquiry. Take three vectors: a,b and c such that a and c are orthogonal. Is it possible to write c as a linear combination of a and b such that: c = ma + nb where m,n are scalars. I was thinking not at first glance but...

Hi, what's a good program/software for writing chemical equations, redox reactions etc. I find Office Word to be a bit slow for that (or perhaps it's my who is slow at using it :P ), And I'm having a difficult time compiling oxidation numbers on top of the elements. Any chemistry friendly...

What's the best and easiest software when it comes to write equations. If I have to write a lot of math language It would be nice to have a program where I can write rapidly. I tried the math editor in Word (office), but every time I need a multiplication symbol I have to find it in the...

Homework Statement Write z = 1 + √3i in polar form Homework Equations z = r (cos\varphi + sin\varphii) The Attempt at a Solution Found the modulus by |z| = √4 = 2 Now I am stuck on this part of finding the argument: Tan-1 (√3) now I am not sure how to go from that to...

Suppose that a fiat coin is tossed 10 times independently. Determine the pf of the number of heads that will be obtained. I'm feeling really out of touch with this material. It seems like any number of heads is equally likely but I know that just can't be right. My reasoning for saying...

So, I was tutoring a friend in math, and he was working in pencil and I noticed that he presses really hard into the paper. In fact, the tip of his pencil broke and I had to loan him my mechanical pencil. That was pretty disastrous because the thin lead snapped every few seconds. He went through...

Homework Statement I have to write a simple program in NASM to read in a character then output what kind of character it is. The Attempt at a Solution There are some things about NASM that confuse me so i marked them. segment .data BUFFLEN equ 1 ; length of buffer CtrlMsg db...

Homework Statement The problems states "All polynomials of the form p(t)= at^2, where a is in R." I'm supposed to see if it is a subspace of Pn. I've already done that but the book's answer is that it spans Pn by Theorem 1, because the set is span{t^2} Homework Equations Theorem states "1 If...

It is about that time in senior year where all my biggest decisions are about to be made. Yea, I'm filling out college applications. Here are my current MAIN choices in ranking of how badly I want to attend: EDIT: I'm majoring in Physics if that matters 1. University of Washington in Seattle...

Homework Statement Write the equation x^2 + y^2 = 1 + sin^2(xy) in polar form assuming x = rcos(\phi) y = rsin(\phi) 0<r, 0<= \phi < 2pi solve for r as a function of \phi The Attempt at a Solution (rcos(\phi))^2 + (rsin(\phi))^2 = 1 + sin^2(r^2cos(\phi)sin(\phi))...

So I have to write out nodal equations for a system that I was given, and I started off by drawing out the flow diagram to see where everything was. I'm having trouble starting the nodal equations though. The attachment has 2 diagrams: figure 1 is the correct diagram that models the thermal...

Homework Statement Write down formulae for dX in terms of dA, dB, dC if: X = [(A) (B^2)] / C Homework Equations I'm using the formula below as this corresponds to this relationship. (dX/X)^2 = (dA/A)^2 + (dB/B)^2 The Attempt at a Solution For the first line, not the...

Homework Statement So the problem is to write a method/function in Java to integrate x2 from a = 1 to b = 2 using the Monte Carlo method. Basically: 1. Generate random points in the range of (0, M) and domain of (a, b), where M is a y value greater than the maximum of f(x) = x2 within (a...

Homework Statement The sequence is a_n = \frac{n^P}{e^n} Homework Equations The Attempt at a Solution If I did L'Hopital's rule P times, would the final product look like: P!\times lim_{n \rightarrow \infty} = \frac{1}{e^n} ?

Is it typical for advisors to want to see their students cry?

At least a go at it... Arch was in his study room contemplating the contents of the last message from Central. The message was brief, only a few words with no outllining explanation - URGENT. RETURN TO BASE. END - and no signature as to whom had sent it. Verification of the encryption code...

How likely is it that an educated (technical and writing background) but not professionally experienced technical writer could make it in the industry if she has difficulty processing verbal information and general (noticeable but not severe) social discomfort? What specific kind of work...

Hey guys. I'm trying to gather some tips that people have acquired that helps them write the Lagrangian for a system. Obviously, the classic examples are drilled into our heads over and over, but just when you think you can tackle any problem the professor throws at you, there is that tricky one...

Is it okay to mix the types of brackets you use when writing out a solution to help make it a bit clearer? For example: If I was completeing the square with: $$ 3x^{2} + 5x -2 = 0 $$ I would factor out the 3 onto square brackets like this: 3 \left[x^{2} + \frac{5}{3}x - \frac{2}{3} \right]...

Since there has been little activity on this part of the forum the past week I have a few questions to pose to those who visit First a definition. A Community Writing project, is what it sounds like. Its a Story written by the community. normally the setting is based on the board it is posted...

Homework Statement k:= {s+t√2:s,t\inQ}, if x1 and x2 \in K, prove x1 +x2\inK Homework Equations The Attempt at a Solution My thought is that x1 and x2 \inK\inQ\subseteqR thus by algerbraic properties X1+x2 =X3 which also \in K. this seems just a little too easy, am i correct in my...

hi i have two file with following data file-1 (named: xyxp.dat) 6 1 1 0 10 3 2 1 5 3 5 4 8 0 0 0 11 1 2 5 4 5 6 4 12 file-2 (named: xyzn.dat) 6 1 0 0 0 2 1 1 0 3 3 2 1 4 1 2 5 5 3 5 4 6 5 6 4 now i want to match each value of the first three columns of file -1 with the corresponding...

Homework Statement A certain drug is being administered intravenously to a hospital patient. Fluid containing 5 mg/cm3 of the drug enters the patient’s bloodstream at a rate of 100 cm3/h. The drug is absorbed by body tissues or otherwise leaves the bloodstream at a rate proportional to the...

In the paper http://arxiv.org/pdf/hep-th/9301028.pdf pages 8-9 Pullin shows how to write the Einstein action in terms of tetrads e^a_I. Part of the proof is: "...the last term yields e_M^{[a} e_N^{b]} \delta^M_{[I} \delta^K_{J]} C_{bK}^{\;\;\; N}. It is easy to check that the prefactor in this...