ターミナルでPythonを立ち上げます．
$ python3
インタプリタでは，以下のようにprint( 2 + 2)と書かずにそのままの計算を書けば実行されます．
>>> print(2 + 2)
4
>>> 2 + 2
4
その他の四則演算は以下のようになります．
>>> 5 - 2
3
>>> 5 * 6
30
>>> 50 - 5 * 6
20
>>> (50 - 5) * 6
270
>>> 8/5
1.6
Pythonでは，数字の型を自動的に認識します．
>>> type(1)
<class 'int'>
>>> type(1.6)
<class 'float'>
>>> 0.6
0.6
>>> .6
0.6
その他の演算は以下の通りです．
>>> 17/3
5.666666666666667
>>> 17 // 3
5
>>> 17 % 3
2
>>> 5 * 5
25
>>> 5 ** 2
25
>>> 5 * 5 * 5 * 5 * 5
3125
当然，変数を使った計算も可能です．
>>> x = 5
>>> x
5
>>> y = 10
>>> y
10
>>> x * y
50
小数点以下を丸めることもできます．
>>> pie = 3.14159265359
>>> pie
3.14159265359
>>> round(pie, 2)
3.14
>>> exit()
Pythonではmathモジュールが準備されていて，とても便利です．
>>> import math
>>> result = math.sqrt(25)
>>> print(y)
>>> print(result)
5.0
>>>
>>> y = math.log2(10)
>>> print(y)
3.321928094887362
mathモジュールの関数について知りたい際には以下のようにhelpを利用することも可能です．
>>> print(help(math))
すると，以下のような様々な関数に関しての説明を見ることができます．
Help on module math:
NAME
math
MODULE REFERENCE
https://docs.python.org/3.6/library/math
The following documentation is automatically generated from the Python
source files. It may be incomplete, incorrect or include features that
are considered implementation detail and may vary between Python
implementations. When in doubt, consult the module reference at the
location listed above.
DESCRIPTION
This module is always available. It provides access to the
mathematical functions defined by the C standard.
FUNCTIONS
acos(...)
acos(x)
Return the arc cosine (measured in radians) of x.
acosh(...)
acosh(x)
Return the inverse hyperbolic cosine of x.
asin(...)
asin(x)
Return the arc sine (measured in radians) of x.
asinh(...)
asinh(x)
Return the inverse hyperbolic sine of x.
atan(...)
atan(x)
Return the arc tangent (measured in radians) of x.
atan2(...)
atan2(y, x)
Return the arc tangent (measured in radians) of y/x.
Unlike atan(y/x), the signs of both x and y are considered.
atanh(...)
atanh(x)
Return the inverse hyperbolic tangent of x.
ceil(...)
ceil(x)
Return the ceiling of x as an Integral.
This is the smallest integer >= x.
copysign(...)
copysign(x, y)
Return a float with the magnitude (absolute value) of x but the sign
of y. On platforms that support signed zeros, copysign(1.0, -0.0)
returns -1.0.
cos(...)
cos(x)
Return the cosine of x (measured in radians).
cosh(...)
cosh(x)
Return the hyperbolic cosine of x.
degrees(...)
degrees(x)
Convert angle x from radians to degrees.
erf(...)
erf(x)
Error function at x.
erfc(...)
erfc(x)
Complementary error function at x.
exp(...)
exp(x)
Return e raised to the power of x.
expm1(...)
expm1(x)
Return exp(x)-1.
This function avoids the loss of precision involved in the direct evaluation of exp(x)-1 for small x.
fabs(...)
fabs(x)
Return the absolute value of the float x.
factorial(...)
factorial(x) -> Integral
Find x!. Raise a ValueError if x is negative or non-integral.
floor(...)
floor(x)
Return the floor of x as an Integral.
This is the largest integer <= x.
fmod(...)
fmod(x, y)
Return fmod(x, y), according to platform C. x % y may differ.
frexp(...)
frexp(x)
Return the mantissa and exponent of x, as pair (m, e).
m is a float and e is an int, such that x = m * 2.**e.
If x is 0, m and e are both 0. Else 0.5 <= abs(m) < 1.0.
fsum(...)
fsum(iterable)
Return an accurate floating point sum of values in the iterable.
Assumes IEEE-754 floating point arithmetic.
gamma(...)
gamma(x)
Gamma function at x.
gcd(...)
gcd(x, y) -> int
greatest common divisor of x and y
hypot(...)
hypot(x, y)
Return the Euclidean distance, sqrt(x*x + y*y).
isclose(...)
isclose(a, b, *, rel_tol=1e-09, abs_tol=0.0) -> bool
Determine whether two floating point numbers are close in value.
rel_tol
maximum difference for being considered "close", relative to the
magnitude of the input values
abs_tol
maximum difference for being considered "close", regardless of the
magnitude of the input values
Return True if a is close in value to b, and False otherwise.
For the values to be considered close, the difference between them
must be smaller than at least one of the tolerances.
-inf, inf and NaN behave similarly to the IEEE 754 Standard. That
is, NaN is not close to anything, even itself. inf and -inf are
only close to themselves.
isfinite(...)
isfinite(x) -> bool
Return True if x is neither an infinity nor a NaN, and False otherwise.
isinf(...)
isinf(x) -> bool
Return True if x is a positive or negative infinity, and False otherwise.
isnan(...)
isnan(x) -> bool
Return True if x is a NaN (not a number), and False otherwise.
ldexp(...)
ldexp(x, i)
Return x * (2**i).
lgamma(...)
lgamma(x)
Natural logarithm of absolute value of Gamma function at x.
log(...)
log(x[, base])
Return the logarithm of x to the given base.
If the base not specified, returns the natural logarithm (base e) of x.
log10(...)
log10(x)
Return the base 10 logarithm of x.
log1p(...)
log1p(x)
Return the natural logarithm of 1+x (base e).
The result is computed in a way which is accurate for x near zero.
log2(...)
log2(x)
Return the base 2 logarithm of x.
modf(...)
modf(x)
Return the fractional and integer parts of x. Both results carry the sign
of x and are floats.
pow(...)
pow(x, y)
Return x**y (x to the power of y).
radians(...)
radians(x)
Convert angle x from degrees to radians.
sin(...)
sin(x)
Return the sine of x (measured in radians).
sinh(...)
sinh(x)
Return the hyperbolic sine of x.
sqrt(...)
sqrt(x)
Return the square root of x.
tan(...)
tan(x)
Return the tangent of x (measured in radians).
tanh(...)
tanh(x)
Return the hyperbolic tangent of x.
trunc(...)
trunc(x:Real) -> Integral
Truncates x to the nearest Integral toward 0. Uses the __trunc__ magic method.
DATA
e = 2.718281828459045
inf = inf
nan = nan
pi = 3.141592653589793
tau = 6.283185307179586
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