Velocity Reviews > float problem

# float problem

Indigo Moon Man
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Posts: n/a

 09-24-2003
for the formula J = I / (12 * 100) where I is low (like about 8 to 15) I
get 0. But when I do it with a calculator it's actually .008333 for example
if I were 10. Is there a way I can get python to recognize the .008333
instead of it just giving me 0?

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Greg Krohn
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 09-24-2003

"Indigo Moon Man" <(E-Mail Removed)> wrote in message
news:bkrai0\$50pag\$(E-Mail Removed)-berlin.de...
> for the formula J = I / (12 * 100) where I is low (like about 8 to 15) I
> get 0. But when I do it with a calculator it's actually .008333 for

example
> if I were 10. Is there a way I can get python to recognize the .008333
> instead of it just giving me 0?
>
>
> --
> Audio Bible Online:
> http://www.audio-bible.com/
>

Normally division with integers gives an integer result losing everything
after the decimal. Couple of things you can do about that, but basically you
have to convert your denominator or divisor to a float before you divide:

J = I / float(12 * 100)

or

J = float(I) / (12 * 100)

Alternativly you could use 12.0 instead of 12 (or 100.0 instead of 100 for
that matter)

J = I / (12.0 * 100)

or

J = I / (12 * 100.0)

And last, but not least, you can import from future to make all division
"lossless":

from __future__ import division
J = I / (12 * 100)

I personally prefer the first one, but they will all work fine.

greg

Gary Herron
Guest
Posts: n/a

 09-24-2003
On Tuesday 23 September 2003 10:34 pm, Indigo Moon Man wrote:
> for the formula J = I / (12 * 100) where I is low (like about 8 to 15) I
> get 0. But when I do it with a calculator it's actually .008333 for
> example if I were 10. Is there a way I can get python to recognize the
> .008333 instead of it just giving me 0?

You're getting bit by the difference between integer and float
division.

In versions of python prior to 2.3 (and in 2.3 under normal
circumstances), division of two integers returns an integer and
division of two floats (or a float and an integer )returns a float:

>>> 2/3

0
>>> 2/3.0

0.66666666666666663
>>> 2.0/3.0

0.66666666666666663
>>>

So one solution would be to make sure the numbers you are dividing are
floats when you want a float in return.

In future version of Python, there will be two dividion operators:
/ will always return a float
// will always return an int

In Python 2.3, you can experiment with the future behavior by starting

>>> from __future__ import division
>>> 2/3

0.66666666666666663
>>> 2//3

0
>>>

So depending on your version of Python, this may be another solution.

Gary Herron

Indigo Moon Man
Guest
Posts: n/a

 09-24-2003
Gary Herron <(E-Mail Removed)> spake thusly:
>
> You're getting bit by the difference between integer and float
> division.
>
> In versions of python prior to 2.3 (and in 2.3 under normal
> circumstances), division of two integers returns an integer and
> division of two floats (or a float and an integer )returns a float:
>

Great! Thank you very much!

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http://www.audio-bible.com/

Indigo Moon Man
Guest
Posts: n/a

 09-24-2003
Greg Krohn <(E-Mail Removed)> spake thusly:
>
> Normally division with integers gives an integer result losing everything
> after the decimal. Couple of things you can do about that, but basically
> you have to convert your denominator or divisor to a float before you
> divide:
>

That's great! Thank you very much for your help!

--
Audio Bible Online:
http://www.audio-bible.com/