Thread: need help with series-- please

  1. #1
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    need help with series-- please

    hey guys i need ur help to do this question please

    Calculate the value of pi = 4- 4/3+ 4/5 4/7 + 4/9 4/11 + ..

    Print a table that shows the approximate value of pi after each of the first 20 terms of this series.

    thanks

    i dont want the answer but i want to know how to do it.

  2. #2
    and the hat of int overfl Salem's Avatar
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    I would suggest using a for loop.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.

  3. #3
    C > C++ duders ggs's Avatar
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    Ignore the man before me. The while loop is superior in every way.
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  4. #4
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    thank u salem
    i know that i have to use for loop
    my problem is how????????????????

    thanks again

  5. #5
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    thanks ggs
    but now i need to know it's work
    i mean how can i do my program
    thanks again

  6. #6
    and the hat of int overfl Salem's Avatar
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    Well you want 20 terms, so how about
    for ( nTerms = 0 ; nTerms < 20 ; nTerms++ )

    Don't think we're being mean or anything, but it's hard to describe what is basically 1 line of code without giving the whole game away.

    Post an effort of your own.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.

  7. #7
    Its hard... But im here swgh's Avatar
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    Quote Originally Posted by ggs View Post
    Ignore the man before me. The while loop is superior in every way.
    Considering the for loop is a while loop condensed into one statement what you said doesnt really make any sense. And Salem is a very seasoned proffesional so he was is correct 99% of the time. Although either loop would work well.
    Double Helix STL

  8. #8
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    thank u all
    here what i did

    pi=pi = 4- 4/3+ 4/5 – 4/7 + 4/9 – 4/11 + …………….
    i= 3,5,7,9,11,................
    for (i=3; i < 20; i = i + 2)
    j=0
    pi=4
    if (j&#37;2==0)
    pi= pi - 4. /i;
    else pi= pi+4. /i;
    cout <<pi<<endl;

    please let me know if what i did is correct or not

  9. #9
    Registered User hk_mp5kpdw's Avatar
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    The first term is 4 (or 4/1).
    The second term is -4/3.
    The third term is 4/5.
    The fourth term is -4/7.

    Do you see what is happening? The denominator increases by 2 every term and the sign flips every term. The sign flip can be done with a multiplication of -1 and the other, well... if you don't know how to add 2 to something you're in the wrong business. The rest is straight addition of those terms.
    Last edited by hk_mp5kpdw; 09-22-2007 at 09:30 PM. Reason: third <> fourth
    "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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  10. #10
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    thanks hk_mp5kpdw
    but if u would explain to me more that will be helpful
    please

  11. #11
    Kiss the monkey. CodeMonkey's Avatar
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    Now now. "Explain to me more." Consider what it is you are having trouble understanding (this might take some thought, maybe a snack or a quick nap), and then ask a question. Use messages to contact board members, not posts.
    "If you tell the truth, you don't have to remember anything"
    -Mark Twain

  12. #12
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    CodeMonkey
    do u know how to do it????

  13. #13
    Kiss the monkey. CodeMonkey's Avatar
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    Anyone who read hk's post knows how to do it. Except you.
    "If you tell the truth, you don't have to remember anything"
    -Mark Twain

  14. #14
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    so what do u want now
    is there any problem if i want to learn how to do it?
    people are diffreent.

    if u dont want to help please dont bother yourself with my problem

  15. #15
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    and i'm sure u dont know how to do it
    Last edited by cs1; 09-22-2007 at 11:27 PM.

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