Python complex() usage and examples

Python built-in functions

When real and imaginary parts are provided, the complex() method will return a complex number, or convert a string to a complex number.

The syntax of complex() is:

complex([real[, imag]])

complex() parameters

Typically, the complex() method takes two parameters:

• real -Real part. If omittedrealit is set to 0 by default.

• imag-Imaginary part. If omittedimagit is set to 0 by default.

If the first parameter passed to this method is a string, it will be interpreted as a complex number. In this case, no second parameter should be passed.

complex() return value

As the name implies, the complex() method returns a complex number.

If the string passed to this method is not a valid complex number, a ValueError exception will be raised.

Note:The string passed to complex() should be real+imagj or real+imagj format

Example1How to create complex numbers in Python?

z = complex(2,　-3)
print(z)
z = complex(1)
print(z)
z = complex()
print(z)
z = complex('5-9j')
print(z)

When running this program, the output is:

(2-3j)
(1+0j)
0j
(5-9j)

Example2Creating complex numbers without using complex()

You can create a complex number without using the complex() method. To do this, you must add 'j' or 'J' to the end of the number.

a =　2+3j
print('a =', a)
print('The type of a is', type(a))
b =　-2j
print('b =', b)
print('The type of b is', type(b))
c = 0j
print('c =', c)
print('The type of c is', type(c))

When running this program, the output is:

a = (2+3j)
The type of a is <class 'complex'>
b = (-0-2j)
The type of b is <class 'complex'>
c = 0j
The type of c is <class 'complex'>

Python built-in functions