I'm new to Sympy, and have realized it is quite nice for calculating and simplifying algebraic expressions.
我是Sympy的新手，并且已经意识到它非常适合计算和简化代数表达式。
However, when when I write fractions of real numbers it returns zero (no problem with fractions of symbols like 'x'). What am I doing wrong?
但是，当我写出实数的分数时，它返回零（像'x'这样的符号分数没有问题）。我究竟做错了什么？
from sympy import *
1./2
Out[2]: 0.5
1/2
Out[3]: 0
2 个解决方案
#1
7
it's because python (2.7) needs a float in denominator or numerator to return a float.
这是因为python（2.7）需要浮点分母或分子来返回浮点数。
in python 3.x any division returns a float
在python 3.x中，任何分区都返回一个浮点数
You can also 'fix' in python 2.7 that by using :
您还可以使用以下命令在python 2.7中“修复”：
from __future__ import division
In fact python follow the integer division rules and return an integer and not a float number
实际上python遵循整数除法规则并返回整数而不是浮点数
#2
0
1/2 isn't using SymPy at all. This is just evaluated by Python. Take a read of http://docs.sympy.org/latest/tutorial/gotchas.html#two-final-notes-and (I actually recommend reading through the whole SymPy tutorial).
1/2根本没有使用SymPy。这只是由Python评估。阅读http://docs.sympy.org/latest/tutorial/gotchas.html#two-final-notes-and（我实际上建议阅读整个SymPy教程）。
Basically, if you are using SymPy, you probably want a rational number, which you can get with Rational(1, 2). An easier way to type this is S(1)/2. The S function converts 1 into SymPy's Integer(1), which then becomes a Rational when divided by.
基本上，如果您使用SymPy，您可能需要一个有理数，您可以使用Rational（1,2）。输入它的更简单方法是S（1）/ 2。 S函数将1转换为SymPy的Integer（1），然后在除以时成为Rational。
#1
7
it's because python (2.7) needs a float in denominator or numerator to return a float.
这是因为python（2.7）需要浮点分母或分子来返回浮点数。
in python 3.x any division returns a float
在python 3.x中，任何分区都返回一个浮点数
You can also 'fix' in python 2.7 that by using :
您还可以使用以下命令在python 2.7中“修复”：
from __future__ import division
In fact python follow the integer division rules and return an integer and not a float number
实际上python遵循整数除法规则并返回整数而不是浮点数
#2
0
1/2 isn't using SymPy at all. This is just evaluated by Python. Take a read of http://docs.sympy.org/latest/tutorial/gotchas.html#two-final-notes-and (I actually recommend reading through the whole SymPy tutorial).
1/2根本没有使用SymPy。这只是由Python评估。阅读http://docs.sympy.org/latest/tutorial/gotchas.html#two-final-notes-and（我实际上建议阅读整个SymPy教程）。
Basically, if you are using SymPy, you probably want a rational number, which you can get with Rational(1, 2). An easier way to type this is S(1)/2. The S function converts 1 into SymPy's Integer(1), which then becomes a Rational when divided by.
基本上，如果您使用SymPy，您可能需要一个有理数，您可以使用Rational（1,2）。输入它的更简单方法是S（1）/ 2。 S函数将1转换为SymPy的Integer（1），然后在除以时成为Rational。