Working with decimal points
How come:
sum = 1/4 print sum returns 0? 1/4=0.25, not 0. How do I fix this?  /usr/bin/byte 
Re: Working with decimal points
Byte wrote:
> How come: > > sum = 1/4 > print sum > > returns 0? 1/4=0.25, not 0. How do I fix this? Make sure there is at least one float in your equation. In your example Python is doing interger math for you and returing the floor. You need to give it a hint that you would like to do floating point math. >>> sum = 1.0/4 >>> print sum 0.25 >>> sum = 1/4.0 >>> print sum 0.25 >>> 
Re: Working with decimal points
That dosnt work either:
sum = 0.1+1/4 print sum Just returns 0.1 
Re: Working with decimal points
"Byte" wrote:
> How come: > > sum = 1/4 > print sum > > returns 0? because 1 and 4 are integer objects, so 1/4 is an integer division, which rounds down to the nearest integer. > 1/4=0.25, not 0. How do I fix this? use floating point numbers: 1.0/4.0 = 0.25 or convert one of the numbers to a float: float(1)/4 = 0.25 </F> 
Re: Working with decimal points
Fredrik Lundh's way works: thank a million!

Re: Working with decimal points
Byte wrote:
> That dosnt work either: > > sum = 0.1+1/4 > print sum > > Just returns 0.1 That's because the 1/4 is executed first, and the problem mentioned still applies (i.e. you get a 0, then add it to 0.1). The best fix for you might be simply to place this line at the start (before all other code) of your module: from __future__ import division That will change the way simple division works to give you the results you expected. See the online docs for more background on this. Peter 
Re: Working with decimal points
On Sat, 08 Apr 2006 08:21:06 0700, Byte wrote:
> How come: > > sum = 1/4 > print sum > > returns 0? 1/4=0.25, not 0. How do I fix this? By default, / does integer division, not floating point. In integer division, 1/4 is 0, exactly as calculated. (How many fours go into one? Zero fours go into one, with one remainder.) There are two ways to change this: (1) Convert at least one of the numbers to a float first: >>> 1.0/4 0.25 >>> 1/float(4) 0.25 but be careful, this one doesn't do what you want: >>> float(1/4) 0.0 (2) Run the following command at the start of your program or in your interactive session: >>> from __future__ import division Now division will behave as you expect: >>> 1/4 0.25 and you can use // for integer division. Now that you can do floating point division, I peer into my crystal ball and predict your next question: why is Python so inaccurate? >>> 1/10 0.10000000000000001 Answer: it isn't. You've discovered a mathematical limitation that 1/10 cannot be written exactly in any fixed number of binary places, just like 1/3 cannot be written exactly in any fixed number of decimal places. See also: http://www.python.org/doc/faq/genera...soinaccurate http://docs.python.org/tut/node16.html Hope this helps.  Steven. 
Re: Working with decimal points
Byte wrote: > That dosnt work either: > > sum = 0.1+1/4 > print sum > > Just returns 0.1 You get precedence right? Your equation does not evaluate from left to right. 1/4 happens first, and since there are no floats you get 0. in that equation you basically are doing this: sum = 1/4 print sum 0 sum = 0.1 + sum print sum 0.1 
Re: Working with decimal points
"Byte" wrote:
> That dosnt work either: > > sum = 0.1+1/4 > print sum > > Just returns 0.1 division has higher precedence than addition, so 1/4 is calculated first, and the result is then added to 0.1. and as I've already explained, 1/4 is an integer division, so the result is rounded down to the the nearest integer (0). in other words, your expression boils down to 0.1 + 0 which is 0.1 [1]. the precedence order is explained here: http://docs.python.org/ref/summary.html </F> 1) or at least a close approximation of it; see http://docs.python.org/tut/node16.html 
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