# 基本
status = True
# インデントに注意
print('*** Now I am going to check status ***')
# ifによる分岐
if status:
print('status is True') # インデントが１段下がる
else:
print('status is False') # ここも１段下がる
# ここからインデントが戻る
print('*** Checking status is done ***')
*** Now I am going to check status *** status is True *** Checking status is done ***
# 入れ子にするなどより細かい制御
a = 1
b = 2
c = 3
print('** A little more complicated example ***')
if a:
print('a = ', a)
# ifを入れ子にする
if a + b > c:
print('a + b > c')
elif a + b < c:
print('a + b < c')
elif a + b == c:
# さらに入れ子にする
if c >= 0:
print('a + b = c and c >= 0')
else:
print('a + b = c and c < 0')
else:
# passを使って「何もしない」ことを明示することもできる
pass
# トップレベルのifに対応するelseは省略
** A little more complicated example *** a = 1 a + b = c and c >= 0
#
# 論理演算子を使う例
#
print('** Use logical operators for complex conditionals ***')
if a < b and a < c:
print('a is smaller than both b and c')
if a < b or a < c:
print('a is smaller than either b or c')
if (a == 1 and a + b == c) or not (a == 1 and b == 2 and c == 3):
print('example of complex conditional')
** Use logical operators for complex conditionals *** a is smaller than both b and c a is smaller than either b or c example of complex conditional
# 一番シンプルな例
for i in range(5):
print(i)
0 1 2 3 4
# 1つおきのループ
for i in range(0, 5, 2):
print('i = ', i)
print('i + 1 = ', i+1)
i = 0 i + 1 = 1 i = 2 i + 1 = 3 i = 4 i + 1 = 5
# 2重ループの例
for i in range(1, 3):
for j in range(1, 5):
print('i = ', i, ', j = ', j, ', i*j = ', i*j)
i = 1 , j = 1 , i*j = 1 i = 1 , j = 2 , i*j = 2 i = 1 , j = 3 , i*j = 3 i = 1 , j = 4 , i*j = 4 i = 2 , j = 1 , i*j = 2 i = 2 , j = 2 , i*j = 4 i = 2 , j = 3 , i*j = 6 i = 2 , j = 4 , i*j = 8
# テイラー展開の公式でsin(x)の近似値を求める
import math
x = 0.2
print('*** Taylor expansion of sin(x) ***')
y = x
a = x
i = 1
print('x = ', x)
print('i = ', i, ' --- sin(x) = ', y)
for i in range(3, 10, 2):
a = -a / ((i-1)*i) * x**2
y = y + a
print('i = ', i, ' --- sin(x) = ', y)
print('exact --- sin(x) = ', math.sin(x))
*** Taylor expansion of sin(x) *** x = 0.2 i = 1 --- sin(x) = 0.2 i = 3 --- sin(x) = 0.19866666666666669 i = 5 --- sin(x) = 0.19866933333333336 i = 7 --- sin(x) = 0.19866933079365082 i = 9 --- sin(x) = 0.19866933079506174 exact --- sin(x) = 0.19866933079506122
# 一番シンプルな例
i = 0
while i < 5:
print(i)
i += 1
0 1 2 3 4
# テイラー展開の公式でsin(x)の近似値が真の値に十分近づくまで計算する
import math
x = 0.2
i = 1
y = x
a = x
ytrue = math.sin(x)
print('i = ', i, ' --- sin(x) = ', y)
while abs((ytrue - y)/ytrue) > 1.0e-10:
i += 2
a = -a / ((i-1)*i) * x**2
y = y + a
print('i = ', i, ' --- sin(x) = ', y)
print('approximated = ', y)
print('exact = ', ytrue)
print('rel. error = ', abs((ytrue-y)/ytrue))
i = 1 --- sin(x) = 0.2 i = 3 --- sin(x) = 0.19866666666666669 i = 5 --- sin(x) = 0.19866933333333336 i = 7 --- sin(x) = 0.19866933079365082 approximated = 0.19866933079365082 exact = 0.19866933079506122 rel. error = 7.0992315183418576e-12
i = 1
while True:
i += 1
if i%2 == 0:
print('Multiple of 2 --- ', i)
continue
elif i%3 == 0:
print('Multiple of 3 --- ', i)
continue
elif i%5 == 0:
print('Multiple of 5 --- ', i)
continue
elif i >= 10:
print('Exit')
break
print('Not a multiple of 2, 3, 5 --- ', i)
Multiple of 2 --- 2 Multiple of 3 --- 3 Multiple of 2 --- 4 Multiple of 5 --- 5 Multiple of 2 --- 6 Not a multiple of 2, 3, 5 --- 7 Multiple of 2 --- 8 Multiple of 3 --- 9 Multiple of 2 --- 10 Exit
# 関数定義
def square(x):
return x**2
# 関数呼び出し
square(2.0)
4.0
### 以下でエラーになるところでも，このセルを2回目以降に評価するときにはエラーにならない！
### エラーになるかどうかをチェックするにはメニューからJupyterカーネルを再起動しよう
# 以下の呼び出しはエラー(この時点ではhelloは定義されていない)
#hello1()
def hello2(name):
hello1() # 実行時にhello1が定義済みであればOK
print('I am', name)
# 以下の呼び出しもエラー(この時点ではhello2が呼び出すhello1は定義されていない)
#hello2('John')
def hello1():
print('Hello')
hello1()
hello2('John')
Hello Hello I am John
import math
# approximation of exp(x) via taylor expansion up to order n
def exp_taylor(x, n):
c = 1.0
f = 1.0
for i in range(n):
c /= (i+1)
f += c * x**(i+1)
return f
print('--- exp_taylor ---')
x = 0.5
print('x = ', x)
print('1st = ', exp_taylor(x, 1))
print('2nd = ', exp_taylor(x, 2))
print('3rd = ', exp_taylor(x, 3))
print('4th = ', exp_taylor(x, 4))
print('5th = ', exp_taylor(x, 5))
print('6th = ', exp_taylor(x, 6))
print('7th = ', exp_taylor(x, 7))
print('8th = ', exp_taylor(x, 8))
print('exact = ', math.exp(x))
--- exp_taylor --- x = 0.5 1st = 1.5 2nd = 1.625 3rd = 1.6458333333333333 4th = 1.6484375 5th = 1.6486979166666667 6th = 1.6487196180555554 7th = 1.6487211681547618 8th = 1.6487212650359622 exact = 1.6487212707001282
# global variables for fibonacci
a =-1
b = 1
def fibonacci():
# a and b refer to the global variables
global a, b
c = a + b
a = b
b = c
return c
print('--- fibonacci ---')
for i in range(20):
print(fibonacci())
--- fibonacci --- 0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597 2584 4181
import sys
# sysオブジェクトの属性versionにアクセス
sys.version
'3.8.16 | packaged by conda-forge | (default, Feb 1 2023, 16:05:36) \n[Clang 14.0.6 ]'
s = 'python'
# 大文字に変換した文字列を返す
s.upper()
'PYTHON'
# 小文字に変換した文字列を返す
s.lower()
'python'
# 先頭を大文字，以降を小文字にした文字列を返す
s.capitalize()
'Python'