英文:
sympy.Rational vs fractions.Fraction Comparison
问题
有区别吗？如果有，是什么？有什么优缺点？如果在Python中有其他实现有理数的方式，可以在比较中包括那些。
英文:
Are there differences? if so, what are they? What are the advantages and disadvantages? If there are other implementations of rational numbers in python, feel free to include those in the comparison.
答案1
得分: 0
如果你只是在寻找一个用于普通数值计算的有理数实现，那么最好使用fractions.Fraction，它专门用于这种情况。SymPy的Rational类有一些不同，因为它是符号表达式框架的一部分，与简单数字的实现相比，它带有一些额外开销。与其他替代方案相比，只有在使用SymPy进行符号计算时才真正有意义使用SymPy的Rational。
在内部，SymPy本身将使用其QQ类型进行更高效的有理数数值计算。如果安装了gmpy2，则QQ指的是gmpy2.mpq，它比Rational或Fraction都更高效。如果没有安装gmpy2，则QQ指的是SymPy的内部PythonMPQ类型，它类似于Fraction。
英文:
If you are just looking for an implementation of rational numbers for ordinary numeric calculations then it is better to use fractions.Fraction which is intended purely for that case. SymPy's Rational class is somewhat different because it is part of a framework of symbolic expressions and that carries some overhead compared to just an implementation of simple numbers. Compared to the alternatives it only really makes sense to use SymPy's Rational as part of symbolic calculations with SymPy.
Internally SymPy itself will use its QQ type for more efficient numeric calculations with rational numbers. If gmpy2 is installed then QQ refers to gmpy2.mpq which is much more efficient than either Rational or Fraction. If gmpy2 is not installed then QQ refers to SymPy's internal PythonMPQ type which is similar to Fraction.
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