Python Exponent – 4 Operators Every Coder Must Know

Python has four ways to calculate the n-th power (exponent) of x so that xⁿ=x*x*...*x that multiplies the base x with itself, and repeating this n-times.

• Method 1: Use the double-asterisk operator such as in x**n.
• Method 2: Use the built-in pow() function such as in pow(x, n).
• Method 3: Import the math library and calculate math.pow(x, n).
• Method 4: Import the NumPy library and calculate np.power(x, n).

Let’s dive into these four methods one by one!

Method 1: Double-Asterisk x**n

The double asterisk (**) symbol is used as an exponentiation operator. The left operand is the base and the right operand is the power. For example, the expression x**n multiplies the value x with itself, n times.

Let’s have a look at a couple of simple examples:

>>> 2**2
4
>>> 2**3
8
>>> 2**4
16
>>> 2**5
32
>>> -3**3
-27

You can also raise to a negative power in which case, the whole expression is inverted such that x**-n == 1/(x**n).

>>> 2**-3
0.125
>>> 2**-2
0.25

Method 2: Built-In pow(x, n)

For pow(x, y), the pow() function returns the value of x raised to the power y. It performs the same function as the power operator ** , i.e. x**y, but differs in that it comes with an optional argument called mod.

Here are a couple of examples without the mod argument:

>>> pow(5, 2)
25
>>> pow(-3, 3)
-27
>>> pow(2, -2)
0.25

If we have a mod argument such as z in pow(x, y, z), the function first performs the task of raising x to the power y and then that result is used to perform the modulo task with respect to z. It would be the equivalent of (x**y) % z .

Here are three examples with the mod argument:

>>> pow(14, 7, 5)
4
>>> pow(-8, 3, 5)
3
>>> pow(2, 4, -3)
-2

Method 3: math.pow(x, n)

The math.pow(x, n) function raises x to the power of n. It calculates the exponent function. The difference to the built-in pow() function is that it doesn’t allow the optional mod argument and it always returns a float, even if the input arguments are integers.

Consider the following examples that show how to use it with integer arguments, float arguments, negative bases, and negative exponents:

>>> math.pow(2, 3)
8.0
>>> math.pow(2.3, 3.2)
14.372392707920499
>>> math.pow(-2, 3)
-8.0
>>> math.pow(2, -3)
0.125

Method 4: numpy.power(x, n)

The NumPy library has a np.power(x, n) function that raises x to the power of n. While the inputs can be arrays, when used on numerical values such as integers and floats, the function also works in the one-dimensional case.

>>> np.power(2, 2)
4
>>> np.power(2, 3)
8
>>> np.power(-2, 3)
-8
>>> np.power(2.0, -3)
0.125

However, if you try to raise an integer to a negative power, NumPy raises an error:

>>> np.power(2, -3)
Traceback (most recent call last):
  File "<pyshell#25>", line 1, in <module>
    np.power(2, -3)
ValueError: Integers to negative integer powers are not allowed.

To fix it, convert the first integer argument to a float value, for example using the float() function.

Summary

You’ve learned four ways to calculate the exponent function in Python.

Method 1: Use the double-asterisk operator such as in x**n.

Method 2: Use the built-in pow() function such as in pow(x, n).

Method 3: Import the math library and calculate math.pow(x, n).

Method 4: Import the NumPy library and calculate np.power(x, n).

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Arithmetic Operators

Arithmetic operators are syntactical shortcuts to perform basic mathematical operations on numbers.