Re: This calculation is just wrong / computer can't count!

".rhavin grobert" <clqrq@xxxxxxxx> wrote in message
news:1191861092.018376.265480@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On 8 Okt., 11:43, "GT" <ContactGT_remo...@xxxxxxxxxxx> wrote:
I disagree:
0.3 is accurate (correct), but not very precise - only 1 decimal place
0.333 is accurate (correct) and precise to 3 decimal places
0.33333333 is accurate (correct) and precise to 8 decimal places
0.33333334 is inaccurate (*WRONG*) and precise to 8 decimal places-

You seem to have a very wired definition of correctness and
accuracity.

if 0.333 is accurate for you than your error is 0.000333333...
by stating 0.33333334 your error is -0.0000000166666666...

so with the statement you defined as wrong your closer to the real
value then with the one you stated as accurate.

One problem here is everyone seems to be banding around the words precise
and accurate - they have different meanings. Precision is the number of
detail in something - the number of decimal palces. Accuracy is how
*correct* something is. Example; 0.83 is accurate (mathematically correct),
but not very precise. 0.83333333333337 is very precise, but not accurate or
in other words mathematically 'wrong'. I don't need my intermediary
calculations stored to a high level of precision (only require calculations
to work to 6 or more digits), but I need these calculations to be accurate
(mathematically correct). If you base a series of calculations on a
fundamentally flawed number, then once it has been squared a few times and
multiplied / divided by some other numbers that are incorrect beyond the
16th digit, then the calculations starts to display problems. The algorithm
works perfectly on paper and when run through a calculator, but not when
programmed in C++.


.

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