From: Panagiotis Atmatzidis <atma@...>
Date: 2009-12-19T08:28:03+09:00
Subject: Re: Question about sum of fibonacci sequene [PROJECT EULER]

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Hello,
On 18 Δεκ 2009, at 10:23 μ.μ., Rob Biedenharn wrote:

> On Dec 18, 2009, at 2:50 PM, Panagiotis Atmatzidis wrote:
> 
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>> Dear Sirs,
>> 
>> Just to improve my programming skills and experience I found amusing solving problems like the ones posed by project Euler. Doing so, using Ruby is a joy, compared to Objective-C that I've used for the same purpose in the past.
>> 
>> I'm stuck in the second problem though. Here is the issue:
>> 
>> Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be:
>> 
>> 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...
>> 
>> Find the sum of all the even-valued terms in the sequence which do not exceed four million.
>> 
>> I think that my code solves it. Works when I test it to smaller fractions, can someone reply if there's something wrong with this snippet:
>> - ---------------
>> # fibonacci
>> 
>> a = 1
>> b = 0
>> sum = 0
>> while a <= 4000000
>> # get the old value of "a"
>> c = a + b
>> #puts c
>> if (c % 2 != 0)
> 
> Note: c % 2 != 0 is only true for ODD values of c and you wanted EVEN values.  Change the 4000000 to be 10 and you ought to see the difference: 1, 2, 3, 5, 8 means 1+3+5=9 for odds and 2+8=10 for evens

omg. I missread that part. Yes I thought it was asking for odd numbers... sorry lol.

> 
>> sum = sum + c
> 
> you could do:
> puts [ c, sum ].inspect
> to see the c's that are being added

thanks for the hint.

> 
>> end
>> b = a
>> a = c
>> end
>> 
>> puts sum
>> - ---------------
>> 
>> Well my result is: 10316618 . I know that the original Fibonacci sequence will have a (+1) in the beginning of the loop, but (probably) for the sake of convenience is ignored. The system however returns a "false error" in both 10316618 and 10316618 + 1.
> 
> Your sequence will be 1, 1, 2, 3, 5, 8, 13, ...
> If you initialize b=1, then you should get 1, 2, 3, 5, 8, 13, ...
> 
>> 
>> Thanks in advanced & best regards
>> 
>> Panagiotis (atmosx) Atmatzidis
>> 
>> email:	atma@convalesco.org
>> URL:	http://www.convalesco.org
> 
> 
> Once you get the right answer, you should think about why the value of your first guess is off to the degree that it is.
> 
> -Rob
> 
> Rob Biedenharn		http://agileconsultingllc.com
> Rob@AgileConsultingLLC.com
> 
> 
> 
> 

Thanks for the pointers

Panagiotis (atmosx) Atmatzidis

email:	atma@convalesco.org
URL:	http://www.convalesco.org
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- --
The wise man said: "Never argue with an idiot. They bring you down to their level and beat you with experience."

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