Fractions in fibonacci series

This is a discussion on Fractions in fibonacci series within the C Programming forums, part of the General Programming Boards category; i've been sitting here for 2 hours searching through info sites and forums getting absolutely nothing out of it. its ...

  1. #1
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    Fractions in fibonacci series

    i've been sitting here for 2 hours searching through info sites
    and forums getting absolutely nothing out of it. its a simple
    problem i have. how to add fractions in c:

    where a/b + c/d == x/y

    can someone point me in the right direction?

  2. #2
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    You treat fractions as ordered pairs of integers, and reduce them to lowest terms if they aren't already, using the Euclidean algorithm

    http://en.wikipedia.org/wiki/Euclidean_algorithm

    to compute the GCD of the numerator and denominator and then divide both by it. In the case of adding fractions, use the formula

    a/b + c/d == (ad + bc)/bd

    followed by reduction to lowest terms as described above.

  3. #3
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    You better try again: That formula does not work for the following two fractions of adding 1/3 and 1/5. According to the formula above, this would be equivalent to 3/5, whereas the real answer is 8/15. Or is my arithmetic that bad??

  4. #4
    The larch
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    Yes, your arithmetic is bad (1 * 5 + 1 * 3)/(3 * 5) == 8 / 15

    If you tried it programmatically then a / b * c != a / (b * c) although the parenthesis should not be required by human conventions (multiplication has higher precedence in algebraic notation?)
    Last edited by anon; 01-10-2008 at 12:13 PM.
    I might be wrong.

    Thank you, anon. You sure know how to recognize different types of trees from quite a long way away.
    Quoted more than 1000 times (I hope).

  5. #5
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    mea culpa!!

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