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  • Showing only topics with the tag "mathematics". Back to normal view
    1. IOS app to train super basic (pre)algebra skills. Free or freemium.

      I know those are easy to find on children's education materials, but the keyword here is simple. Anything kiddie, requiring too many clicks or that takes 3 seconds is off the table. I kinda need...

      I know those are easy to find on children's education materials, but the keyword here is simple. Anything kiddie, requiring too many clicks or that takes 3 seconds is off the table.

      I kinda need to brush up on my super basic reasoning. In part, because a grown man should know the time table by heart, and in part, because I wanna convince myself that I did not get brain damage after being hit by a car (there's really nothing indicating that, I'm just paranoid).

      I'm looking for something simple that presents me with the multiplication table and or simple calculations to answer under a time frame. The requirement for iOS is that my computer is broken.

      And it really can be super simple, even something I open from a mobile web browser or transfer to my Kindle.

      Additionally: there is no need for if to be an app. A huge list of exercises (with answers) would be greatly helpful.

      Thanks!

      6 votes
    2. Does anyone have resources for an introduction to semidefinite programming?

      I'm interested in the subject, but don't know where to begin investigating it. I tried to look over the code for SeDuMi, but it is much more massive than I had realized. I have a background in...

      I'm interested in the subject, but don't know where to begin investigating it. I tried to look over the code for SeDuMi, but it is much more massive than I had realized. I have a background in mathematics, if anyone can point me towards a textbook.

      5 votes
    3. Periodic functions

      Does there exist a function that does not include any trigonometric function in its definition that has similar properties (periodicity, for instance) as trigonometric functions? I can't think of...

      Does there exist a function that does not include any trigonometric function in its definition that has similar properties (periodicity, for instance) as trigonometric functions? I can't think of any, and this strikes me as a bit surprising.

      Edit: I thought of a simple answer: piecewise functions can achieve this!

      6 votes
    4. Real Numbers - Why? Why not computable numbers?

      Do we have any mathematicians in the house? I've been wondering for a while why math is usually focused around real numbers instead of computable numbers - that is the set of numbers that you can...

      Do we have any mathematicians in the house? I've been wondering for a while why math is usually focused around real numbers instead of computable numbers - that is the set of numbers that you can actually be computed to arbitrary, finite precision in finite time. Note that they necessarily include pi, e, sqrt(2) and every number you could ever compute. If you've seen it, it's computable.

      What do we lose, beyond cantor's argument, by restricting math to computable numbers? By corollary of binary files and therefore algorithms being countable, the computable numbers are countable too, different from reals.

      Bonus points if you can name a real, non-computable number. (My partner replied with "a number gained by randomly sampling decimal places ad infinitum" - a reply as cheeky as the question.) Also bonus points for naming further niceness properties we would get by restricting to computables.

      I've read the wikipedia article on computable numbers and a bit beyond.

      10 votes