Cannot divide

This is a discussion on Cannot divide within the C++ Programming forums, part of the General Programming Boards category; Hello, I have two variables, x and y, inside a loop. X gets the value of an AP (1,3,5,7,...) while ...

  1. #1
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    Cannot divide

    Hello,

    I have two variables, x and y, inside a loop. X gets the value of an AP (1,3,5,7,...) while Y gets the value of a GP (1,-1,1,-1). My problem is that the value of 1(x*y) is rounded by the computer to 0. Here is part of the source code of my program.

    ...
    float value;
    ...
    while (loop_count != max){
    ...
    value += 1/(x*y);
    ...

    What am I doing wrong? How can I fix this?

    Thanks a lot!

  2. #2
    Registered User hk_mp5kpdw's Avatar
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    It may be a problem with the integer division. For starters, you can see if value += 1.0/(x*y) fixes this. Integer division of 1 by some large number will get truncated to 0 and then assigned to value.
    "Owners of dogs will have noticed that, if you provide them with food and water and shelter and affection, they will think you are god. Whereas owners of cats are compelled to realize that, if you provide them with food and water and shelter and affection, they draw the conclusion that they are gods."
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  3. #3
    Registered User axon's Avatar
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    ...also look what type is your 'x' and 'y' variable, and how they are initialized.
    Code:
    double x = 4.0; //something like that
    axon

    some entropy with that sink? entropysink.com

    there are two cardinal sins from which all others spring: Impatience and Laziness. - franz kafka

  4. #4
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    Originally posted by hk_mp5kpdw
    It may be a problem with the integer division. For starters, you can see if value += 1.0/(x*y) fixes this. Integer division of 1 by some large number will get truncated to 0 and then assigned to value.
    Thank you, it worked out.
    I've got another question:

    The program I'm creating calculates pi with Leibniz procedure [4*(1/1 - 1/3 + 1/5 - 1/7 + ...)]. The problem is that it only gives precision of 4 characters (3,1415). How can I increase this?

    Thanks!

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