Hi,
It seems decimal object will always be larger than float in
comparasion, which goes against common sense:
>>from decimal import Decimal
a = Decimal('0.5')
a 99999
False
>>a 99999.0
True
It seems to me that rather than allowing this to happen, comparasion
between the two should either be made correct (by convertion decimal
to float e.g.) or forbidden, like arithmatic operations between the
two types.
--
Hong Yuan
´ó¹Ü¼ÒÍøÉϽ¨²Ä³ ¬ÊÐ
×°ÐÞ×°ä꽨²ÄÒ»Õ ¾Ê½¹ºÎï http://www.homemaster.cn 4  1466 
I still don't see why such a module exists.
On 5 mayo, 21:52, "Yuan HOng" <hongyuan1...@g mail.comwrote:
Hi,
It seems decimal object will always be larger than float in
comparasion, which goes against common sense:
>from decimal import Decimal
a = Decimal('0.5')
a 99999
False
>a 99999.0
True
It seems to me that rather than allowing this to happen, comparasion
between the two should either be made correct (by convertion decimal
to float e.g.) or forbidden, like arithmatic operations between the
two types.
--
Hong Yuan
´ó¹Ü¼ÒÍøÉϽ¨²Ä³ ¬ÊÐ
×°ÐÞ×°ä꽨²ÄÒ»Õ ¾Ê½¹ºÎïhttp://www.homemaster.cn
Gasto wrote:
I still don't see why such a module exists.
There are 2.0 types of programmers: those who always use floating point,
and those who know how to use them.
Dennis Lee Bieber wrote:
On Tue, 6 May 2008 11:52:10 +0800, "Yuan HOng" <ho**********@g mail.com>
declaimed the following in comp.lang.pytho n:
>It seems to me that rather than allowing this to happen, comparasion
between the two should either be made correct (by convertion decimal
to float e.g.) or forbidden, like arithmatic operations between the
two types.
Why should decimal be coerced to float? Maybe float should be
coerced to decimal?
Or... the programmer should explicitly specify what comparison is
wanted -- if any...
Or... Isn't Python 3.x supposed to forbid mixed type comparisons
unless the types implement suitable handling?
Bottom line is that it shouldn't silently return something insane.
99999.0 is surely exactly representable in any modern floating point
system, being a floating point representing of an integer, so silently
returning a completely invalid comparison is a tremendously bad idea.
It's a bug.
--
Erik Max Francis && ma*@alcyone.com && http://www.alcyone.com/max/
San Jose, CA, USA && 37 18 N 121 57 W && AIM, Y!M erikmaxfrancis
Can I walk with you / 'Till the day that the world stops turning
-- India Arie
On May 6, 1:31 am, Dennis Lee Bieber <wlfr...@ix.net com.comwrote:
On Tue, 6 May 2008 11:52:10 +0800, "Yuan HOng" <hongyuan1...@g mail.com>
declaimed the following in comp.lang.pytho n:
It seems to me that rather than allowing this to happen, comparasion
between the two should either be made correct (by convertion decimal
to float e.g.) or forbidden, like arithmatic operations between the
two types.
Why should decimal be coerced to float? Maybe float should be
coerced to decimal?
Or... the programmer should explicitly specify what comparison is
wanted -- if any...
Or... Isn't Python 3.x supposed to forbid mixed type comparisons
unless the types implement suitable handling?
Yes, it is fixed in 3.0. Unfortunately it's well established
behaviour in 2.x, so it won't be changing there. Don't bother
reporting a bug about this unless it's about 3.0. This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics | |
by: Batista, Facundo |
last post by:
Here I send it.
Suggestions and all kinds of recomendations are more than welcomed.
If it all goes ok, it'll be a PEP when I finish writing/modifying the code.
Thank you.
.. Facundo
|
by: Batista, Facundo |
last post by:
People:
I'll post a reviewed version of the PEP.
The only differences with the previous one will be the treatmen to float in
both explicit and implicit construction:
------------
In Explicit construction:
|
by: jbauer |
last post by:
I was interested in playing around with Decimal and
subclassing it. For example, if I wanted a special
class to permit floats to be automatically converted
to strings.
from decimal import Decimal
class MyDecimal(Decimal):
def __init__(self, value):
if isinstance(value, float):
|
by: Kay Schluehr |
last post by:
I wonder why this expression works:
>>> decimal.Decimal("5.5")**1024
Decimal("1.353299876254915295189966576E+758")
but this one causes an error
5.5**1024
Traceback (most recent call last):
|
by: Kuljit |
last post by:
I am doing Engineering(B.Tech) in Computer Science.
I have a question for which i am struggling to write a C code(program).
It struck me when we were being taught about a program which counts the
number of digits in a given number.
I request to help me out in solving the below said question.
Ask the user to enter a decimal/float number(eg. 32.8952), then count
the number of digits in that number after the decimal point(4 in this
case).
| | |
by: Lennart Benschop |
last post by:
Python has had the Decimal data type for some time now. The Decimal data
type is ideal for financial calculations. Using this data type would be
more intuitive to computer novices than float as its rounding behaviour
matches more closely what humans expect. More to the point: 0.1 and 0.01
are exact in Decimal and not exact in float.
Unfortunately it is not very easy to access the Decimal data type. To obtain
the decimal number 12.34 one...
|
by: Wojciech Walczak |
last post by:
2008/5/6, Yuan HOng <hongyuan1306@gmail.com>:
Looks like a nasty bug.
a 99999.0 returns True because NotImplemented 99999.0 returns True.
a < 99999.0 returns False because NotImplemented < 99999.0 returns False.
As you can see the real comparision has nothing to do with your Decimal number.
I think you can report it at bugs.python.org.
|
by: D'Arcy J.M. Cain |
last post by:
I'm not sure I follow this logic. Can someone explain why float and
integer can be compared with each other and decimal can be compared to
integer but decimal can't be compared to float?
True
True
False
This seems to break the rule that if A is equal to B and B is equal to
C then A is equal to C.
|
by: Terry Reedy |
last post by:
Gerhard Häring wrote:
The new fractions module acts differently, which is to say, as most
would want.
True
Traceback (most recent call last):
File "<pyshell#20>", line 1, in <module>
F(1.0)
File "C:\Program Files\Python30\lib\fractions.py", line 97, in __new__
|
by: Oralloy |
last post by:
Hello folks,
I am unable to find appropriate documentation on the type promotion of bit-fields when using the generalised comparison operator "<=>".
The problem is that using the GNU compilers, it seems that the internal comparison operator "<=>" tries to promote arguments from unsigned to signed.
This is as boiled down as I can make it.
Here is my compilation command:
g++-12 -std=c++20 -Wnarrowing bit_field.cpp
Here is the code in...
|
by: tracyyun |
last post by:
Dear forum friends,
With the development of smart home technology, a variety of wireless communication protocols have appeared on the market, such as Zigbee, Z-Wave, Wi-Fi, Bluetooth, etc. Each protocol has its own unique characteristics and advantages, but as a user who is planning to build a smart home system, I am a bit confused by the choice of these technologies. I'm particularly interested in Zigbee because I've heard it does some...
| | |
by: agi2029 |
last post by:
Let's talk about the concept of autonomous AI software engineers and no-code agents. These AIs are designed to manage the entire lifecycle of a software development project—planning, coding, testing, and deployment—without human intervention. Imagine an AI that can take a project description, break it down, write the code, debug it, and then launch it, all on its own....
Now, this would greatly impact the work of software developers. The idea...
|
by: isladogs |
last post by:
The next Access Europe User Group meeting will be on Wednesday 1 May 2024 starting at 18:00 UK time (6PM UTC+1) and finishing by 19:30 (7.30PM).
In this session, we are pleased to welcome a new presenter, Adolph Dupré who will be discussing some powerful techniques for using class modules.
He will explain when you may want to use classes instead of User Defined Types (UDT). For example, to manage the data in unbound forms.
Adolph will...
|
by: conductexam |
last post by:
I have .net C# application in which I am extracting data from word file and save it in database particularly. To store word all data as it is I am converting the whole word file firstly in HTML and then checking html paragraph one by one.
At the time of converting from word file to html my equations which are in the word document file was convert into image.
Globals.ThisAddIn.Application.ActiveDocument.Select();...
|
by: adsilva |
last post by:
A Windows Forms form does not have the event Unload, like VB6. What one acts like?
|
by: 6302768590 |
last post by:
Hai team
i want code for transfer the data from one system to another through IP address by using C# our system has to for every 5mins then we have to update the data what the data is updated we have to send another system
|
by: muto222 |
last post by:
How can i add a mobile payment intergratation into php mysql website.
| | |
by: bsmnconsultancy |
last post by:
In today's digital era, a well-designed website is crucial for businesses looking to succeed. Whether you're a small business owner or a large corporation in Toronto, having a strong online presence can significantly impact your brand's success. BSMN Consultancy, a leader in Website Development in Toronto offers valuable insights into creating effective websites that not only look great but also perform exceptionally well. In this comprehensive...
| |
