1.#QNAN Solution

[Greg Corradini]

Hello all,
I'm running descriptive stats on mileages from a database (float numbers,
about a million records). My sum returns 1.#QNAN, which I understand from
searching this forum is an error.

While I'm looking for help in solving this problem, I'm more interested in a
general explanation about the cause of this problem. Any ideas?

Thanks
Greg Corradini
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[Grant Edwards]

Re: 1.#QNAN Solution

On 2007-05-08, Greg Corradini <gregcorradini@ gmail.comwrote:

I'm running descriptive stats on mileages from a database
(float numbers, about a million records). My sum returns
1.#QNAN, which I understand from searching this forum is an
error.

Not necessarily. You've ended up with a floating point "not a
number" value (AKA a NaN). That might or might not be an
error. Whether it's an error not not depends on your input
data and your algorithm.

While I'm looking for help in solving this problem, I'm more
interested in a general explanation about the cause of this
problem.

If you're asking how you end up with a NaN, there are several
ways to generate a NaN:

0/0

Inf*0

Inf/Inf

Inf-Inf

Almost any operation on a NaN

http://en.wikipedia.org/wiki/NaN

http://steve.hollasch.net/cgindex/coding/ieeefloat.html

--
Grant Edwards grante Yow! Spreading peanut
at butter reminds me of
visi.com opera!! I wonder why?

[Greg Corradini]

Re: 1.#QNAN Solution


Thanks for you help Grant

Grant Edwards wrote:

>
On 2007-05-08, Greg Corradini <gregcorradini@ gmail.comwrote:
>

>I'm running descriptive stats on mileages from a database
>(float numbers, about a million records). My sum returns
>1.#QNAN, which I understand from searching this forum is an
>error.

>
Not necessarily. You've ended up with a floating point "not a
number" value (AKA a NaN). That might or might not be an
error. Whether it's an error not not depends on your input
data and your algorithm.
>

>While I'm looking for help in solving this problem, I'm more
>interested in a general explanation about the cause of this
>problem.

>
If you're asking how you end up with a NaN, there are several
ways to generate a NaN:
>
0/0
>
Inf*0
>
Inf/Inf
>
Inf-Inf
>
Almost any operation on a NaN
>

http://en.wikipedia.org/wiki/NaN

http://steve.hollasch.net/cgindex/coding/ieeefloat.html

>
--
Grant Edwards grante Yow! Spreading peanut
at butter reminds me of
visi.com opera!! I wonder why?
--

http://mail.python.org/mailman/listinfo/python-list

>
>

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