The complex() function in Python is used to create a complex number, which is a number that has a real part and an imaginary part. Complex numbers are represented as a + bj, where a is the real part and b is the imaginary part (with j denoting the imaginary unit).

Syntax

complex([real[, imag]])

• real (optional): The real part of the complex number. This can be an integer or a float.
• imag (optional): The imaginary part of the complex number. This can also be an integer or a float. If omitted, it defaults to 0.

Return Value

• Returns a complex number represented as a + bj.

Examples

1. Creating a complex number with both real and imaginary parts:

   z1 = complex(2, 3)
   print(z1)  # Output: (2+3j)
   

2. Creating a complex number with only the real part: If you provide only one argument, it will be treated as the real part, and the imaginary part defaults to 0.

   z2 = complex(5)
   print(z2)  # Output: (5+0j)
   

3. Creating a complex number with a negative imaginary part: You can also specify negative values for the imaginary part.

   z3 = complex(4, -2)
   print(z3)  # Output: (4-2j)
   

4. Creating a complex number from a string: You can also create a complex number by passing a string representation of a complex number.

   z4 = complex("1+2j")
   print(z4)  # Output: (1+2j)
   

5. Using float values for both parts: You can use floating-point numbers for both the real and imaginary parts.

   z5 = complex(3.5, 2.5)
   print(z5)  # Output: (3.5+2.5j)
   

6. Using the real and imag attributes: Once you have a complex number, you can access its real and imaginary parts using the .real and .imag attributes.

   print(z1.real)  # Output: 2.0
   print(z1.imag)  # Output: 3.0
   

7. Complex conjugate: You can get the complex conjugate of a complex number using the conjugate() method.

   print(z1.conjugate())  # Output: (2-3j)
   

Summary

• The complex() function creates a complex number in Python, represented as a + bj.
• You can specify both the real and imaginary parts, or just the real part.
• It can accept string representations of complex numbers.
• Complex numbers have properties like accessing their real and imaginary parts and obtaining their conjugate.