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Psuedo-random numbers

  1. Mar 26, 2008 #1
    Hello, i am writing a program that needs fairly random numbers however not true random numbers. I want to write my own formula however i am no mathematician and i need your help. There will be two variables minimum number and maximum number and i will be using the time of day to help generate more randomization.

    thanks sinners
     
  2. jcsd
  3. Mar 31, 2008 #2
    I guess it depends on which programming language you're using, as most programming languages have built in functions which allow you to generate pseudo-random numbers using the time as a seed value. If you're looking for an algorithm in general, check out the wikipedia article and follow the links: http://en.wikipedia.org/wiki/Pseudorandom_number_generator
     
  4. Apr 1, 2008 #3
    Check out the Mersenne twister algorithim. Octave uses it and keeps telling everyone not to use it for cryptography.

    If you want a simpler kind of random number with simple bias, try calling a regular random number, the modding it by a number that does not divide into the size of the placeholder type. i.e. something like

    int a=rand();
    a=a%6;

    This will introduce a slight bias, as a can range from 0-255. Since 256/6 = 42 remainder 4, the numbers 1-4 will get one extra chance to be selected that 5 and 6 do not.
     
  5. Apr 1, 2008 #4
    If you're using the time of the day, then as said above, you can go ahead and use a function that takes the time for that particular language (you can do this in C++ for example). Use these as your seeds and you can go ahead and define your bounds this way.

    Feed this into a random number function if it's built into the language, and you're done.
     
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