Rounding issue when adding floats in python, is this normal?

Posted by thepearson on Stack Overflow See other posts from Stack Overflow or by thepearson
Published on 2010-05-06T23:13:18Z Indexed on 2010/05/06 23:18 UTC
Read the original article Hit count: 199

Filed under:

python

|

floating-point

|

expression

I just wanted to know if this behavior is expected. If so, can someone explain to me why. This has probably been answered elsewhere I can't seem to find it using Google. Probably not searching with the right terms. I am running Ubuntu 10.04.

Python 2.6.5 (r265:79063, Apr 16 2010, 13:09:56) 
[GCC 4.4.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> var = 10.0
>>> var
10.0
>>> var + 5
15.0
>>> var + 5.1
15.1
>>> var + 5.2
15.199999999999999
>>>

© Stack Overflow or respective owner

Related posts about python

unmet dependencies in Ubuntu 12.04

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
I tried today to install a dvb-card on my Ubuntu 12.04 (Linux blauhai-linux 3.2.0-25-generic #40-Ubuntu SMP Wed May 23 20:30:51 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux ). The installation failed with an error. After that, i tried to install python (it was already installed but i got this error): linux:~$… >>> More
How can I get sikuli-ide to work?

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
I installed sikuli-ide with sudo apt-get install sikuli-ide Everything was fine until I tried to start it from the terminal. I typed sikuli-ide But the only response I got was [info] locale: en_US The application was not started, furthermore there is no desktop file and sikuli-ide does not… >>> More
Getting PATH right for python after MacPorts install

as seen on Super User - Search for 'Super User'
I can't import some python libraries (PIL, psycopg2) that I just installed with MacPorts. I looked through these forums, and tried to adjust my PATH variable in $HOME/.bash_profile in order to fix this but it did not work. I added the location of PIL and psycopg2 to PATH. I know that Terminal is… >>> More
call python with system() in R to run a python script emulating the python console

as seen on Stack Overflow - Search for 'Stack Overflow'
I want to pass a chunk of Python code to Python in R with something like system('python ...'), and I'm wondering if there is an easy way to emulate the python console in this case. For example, suppose the code is "print 'hello world'", how can I get the output like this in R? >>> print… >>> More
Python - Calling a non python program from python?

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I am currently struggling to call a non python program from a python script. I have a ~1000 files that when passed through this C++ program will generate ~1000 outputs. Each output file must have a distinct name. The command I wish to run is of the form: program_name -input -output -o1 -o2… >>> More

Related posts about floating-point

Comparing floating point values

as seen on Stack Overflow - Search for 'Stack Overflow'
I just read a statement about the floating point value comparison Floating point values shall not be compared using either the == or != operators. Most floating point values have no exact binary representation and have a limited precision. If so what is the best method for comparing two floating… >>> More
understanding floating point variables

as seen on Stack Overflow - Search for 'Stack Overflow'
There is some problem, i can't understand anyway. look at this code please <script type="text/javascript"> function math(x) { var y; y = x*10; alert(y); } </script> <input type="button" onclick="math(0.011)"> What must be alerted after i click on button? i think 0.11… >>> More
floating point hex octal binary

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I am working on a calculator that allows you to perform calculations past the decimal point in octal, hexadecimal, binary, and of course decimal. I am having trouble though finding a way to convert floating point decimal numbers to floating point hexadecimal, octal, binary and vice versa. The… >>> More
What is a Bias Value of Floating Point Numbers?

as seen on Stack Overflow - Search for 'Stack Overflow'
In learning how floating point numbers are represented in computers I have come across the term "bias value" that I do not quite understand. The bias value in floating point numbers has to do with the negative and positiveness of the exponent part of a floating point number. The bias value of a… >>> More
Why are floating point values so prolific?

as seen on Stack Overflow - Search for 'Stack Overflow'
So, title says it all. Why are floating point values so prolific in computer programming. Due to problems like rounding errors, and not being able to even accurately represent numbers such as 0.1, I really can't see how they got as far as they did. I understand that the computation is faster… >>> More