Python - Math - Algebra and Symbolic Math with SymPy(Summing a Series)

Doing Math with Python

開発環境

• OS X El Capitan - Apple (OS)
• Emacs (Text Editor)
• Python 3.5 (プログラミング言語)

Doing Math with Python: Use Programming to Explore Algebra, Statistics, Calculus, and More! (Amit Saha (著)、No Starch Press)のChapter 4.(Algebra and Symbolic Math with SymPy)、Programming Challenges #3: Summing a Series(No. 2922)を解いてみる。

#3: Summing a Series(No. 2922)

コード(Emacs)

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import sympy

n = sympy.Symbol('n')
term = input('Enter the nth term: ')
num = input('Enter the number of terms: ')

try:
    term = sympy.sympify(term)
except sympy.SympifyError as err:
    print(err)
else:
    s = sympy.summation(term, (n, 1, num))
    sympy.pprint(s)

入出力結果(Terminal, IPython)

$ ./sample3.py
Enter the nth term: s**n/n
Enter the number of terms: 5
 5    4    3    2    
s    s    s    s     
── + ── + ── + ── + s
5    4    3    2     
$ ./sample3.py
Enter the nth term: a+(n-1)*d
Enter the number of terms: 3
3⋅a + 3⋅d
$