Recent content by JCienfuegos

  1. J

    Open Intervals

    I always imagined that the smallest number less than one was the infinitesimal 0.9...., but that cannot be, because that equals one. The only other answer I could come come up with was that only terminating decimals of the form 0.999...9 would be in the interval, but that's no good either. I...
  2. J

    Open Intervals

    Since we all agree that 1 = 0.999..., what does PF think the largest number in the open interval (0,1) is?
  3. J

    MATLAB Matlab redundancies in a two column vector

    Hello I am new to MATLAB and I am trying to perform the task of removing redundancies from a two column vector. One column holds the indices, the other column holds the values. I don't know how to remove the redundant values! Any ideas? I have hear that Unique works, but I have the feeling...
  4. J

    MATLAB Euler's Method in MAtlab

    Hello I have a program for Eulers method >> % Euler's Method for dy/dt = cost k = 1; y0 = 0; npoints = 500; dt = 0.01; y = zeros(npoints,1); % this initializes the vector y to being all zeros t = zeros(npoints,1); y(1) = y0; % the initial condition t(1) = 0.0; for...
  5. J

    Hooke's Law should be exponential.

    I was just thinking, shouldn't hooke's law be represented with an exponential equation? I am thinking that in class, the springs we use for the hooke's law experiment are small, but if they were very large, then the higher coils would be sustaining much more weight than the lower coils, and...
  6. J

    A challenging volume problem

    Well, that is not the answer i got. Now that think about it, my solution may be wrong, but I cannot think why. What I did was this: I imagined the sphere to be resting onto of the x axis, directly on top of the origin. I then tied the leash to the origin. I found the equation of the sphere...
  7. J

    A challenging volume problem

    I tried using this trick in high school. The teacher said what is sin342 or something like that and I put "something between -1 and 1". I got that question wrong.
  8. J

    A challenging volume problem

    Hello everyone This problem is similar to a problem that appeared sometime back on this website called "last geometry challenge, very difficult!" The problem was this: There is a circular field of grass of radius r surrounded by a fence. If aa sheep is tethered to the fence, how long should...