[racket] Am I Missing Something? [HtDP 31.3.1]

Oops. Sorry.  I was interpreting the issue backwards. I don't have an explanation; Luke needs to show his numbers. Or I need to be in the lab where I can run it on Ubuntu, which doesn't seem likely to be the issue anyway.

rac

On Jan 4, 2011, at 1:26 PM, Carl Eastlund wrote:

> Richard,
> 
> We're not looking for an explanation of why the two numbers are
> different.  We're looking for an explanation of why, on Luke's
> machine, unlike anybody else's here, they _aren't_ different.  Somehow
> I don't think portability issues in DrRacket are anybody's homework
> assignment.  So if you have an explanation, please share.  :)
> 
> Carl Eastlund
> 
> On Tue, Jan 4, 2011 at 3:22 PM, Richard Cleis <rcleis at mac.com> wrote:
>> I can explain it, but I don't know if it's revealing a solution.
>> 
>> rac
>> 
>> On Jan 4, 2011, at 12:32 PM, Stephen Chang wrote:
>> 
>>> I get results similar to Carl.
>>> 
>>> Welcome to DrRacket, version 5.0.1.7 [3m].
>>> Language: Intermediate Student.
>>> #i-0.49746596003269394
>>> #i-0.4974659600326953
>>> #i-4974659600326939.0
>>> #i-4974659600326953.0
>>>> (equal? (sum (g-series #i1000)) (accu-sum (g-series #i1000)))
>>> false
>>>> (equal? (* 10e15 (sum (g-series #i1000))) (* 10e15 (accu-sum (g-series #i1000))))
>>> false
>>>> 
>>> 
>>> 
>>> Luke, can you post the output you get?
>>> 
>>> 
>>> 
>>> 
>>> On Tue, Jan 4, 2011 at 10:57 AM, Carl Eastlund <cce at ccs.neu.edu> wrote:
>>>> 
>>>> On Tue, Jan 4, 2011 at 9:38 AM, Luke Jordan <luke.jordan at gmail.com> wrote:
>>>>> All that code came straight out of the text, except that I used if instead
>>>>> of cond.  The sum, accu-sum, and g-series defs are all given.  In your
>>>> 
>>>> Ah, yes, now I see where the accumulator-based sum is.  Sorry, my mistake.
>>>> 
>>>>> results I see a difference.  When I run it at home it's the same.  I can
>>>>> even (equal? (sum (listof number)) (accu-sum (listof number))) and get true.
>>>> 
>>>> No idea what's going on.  Maybe someone else will have an idea.
>>>> 
>>>> --Carl