Try mathematical formulas using Σ with python

-Background -[What is Σ](http://qiita.com/weedslayer/items/25c38c928ad59ba61071#What is Σ) -[What you want to do](http://qiita.com/weedslayer/items/25c38c928ad59ba61071 #What you want to do) -[Check operation with Python](http://qiita.com/weedslayer/items/25c38c928ad59ba61071#Check operation with Python) -[Lighten the example](http://qiita.com/weedslayer/items/25c38c928ad59ba61071 #Lighten the example) -[Extra edition ~ what if ~](http://qiita.com/weedslayer/items/25c38c928ad59ba61071 # Extra edition ~ what if ~)

Background

I come across Σ (sigma) in class
It's been a long time and I can think of how easy it can be expressed using Python.
Gently look
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Give it a try

What is Σ

In a word, it is expressed as sum or (mainly) the sum of a sequence.

Image reprinted from: Learn Sigma Notation Online

See below for detailed usage:

What was the meaning of Σ? [Sequence 9] Sigma 1 What is Sigma? Explain the meaning and calculation of Sigma [High 2 Mathematics / Number B] Sum of sequences ~ Definition and calculation method of sigma Σ: Visual mathematics (math B: sequence

Thing you want to do

Refer to the source, 544x215xsigma.png.pagespeed.ic.f1Iqf-52cp.png

I managed to get it to work with python.

Confirmed operation with Python

Below is the original code

`sigma.py`


def f(x):
    return 2*x + 1

def g(x):
    return (x-1) * (x-3)

def sigma(func, frm, to:
    result = 0;
    for i in range(frm, to+1):
        result += func(i)
    return result

sigma(f, 2, 4) #21
sigma(g, 1, 3) #-1

See here for the detailed flow.

Make this work with Python 3.x

`sigma2.py`


def f(x):
	return 

def sigma(func, frm, to):
	result = 0;
	for i in range(frm, to+1):
		result += func(i)
	print(result)

sigma(f, 1, 10) #21

Lighten the example

Example: Find the sum of the following equations.

this

--- #1

When

math copy.png --- #2 （これが上の画像で言うk番目のa）

Divide into.

First, create a function that gives the answer of # 2.

def f(n):
    return 3 * n - 2

And the function that gives the answer of # 1

def sigma(func, frm, to):
	result = 0; #Answer saucer
	for i in range(frm, to+1):
		result += func(i) 
		#Call the function here. By the way, here i= x
	print(result)

The completed form looks like this

ef f(n):
	return 3 * n - 2  

def sigma(func, frm, to):
	result = 0; #Answer saucer
	for i in range(frm, to+1):
		result += func(i) 
		#Call the function here. By the way, here i= x
	print(result)

sigma(f, 1, 4) #22

Extra edition ~ what if ~

If you come across an expression that doesn't require you to create an expression for f (x)

Delete the argument func of the sigma function
From result + = func (i) to result + = i
This works fine. .. Should be

def sigma2(frm, to):
	result = 0;
	for i in range(frm, to+1):
		result += i
	print(result)

sigma2(1,10) #55