In this article, we will learn about python program to multiply two complex numbers with examples.

Getting Started

Complex numbers are number that can be represented as –

 
a+bj,
Where, a and b are real numbers

For example,
13+4j, 5-14j, 2.3+4j etc.

We have already covered how to

• add two complex numbers
• how to add subtract two complex numbers

Now, we will learn about how to multiply two complex numbers in python. For example,

If a = 30+4j and b = 15+2j, then a x b = 442+120j

We have to do such multiplication of complex numbers using python programming.

We can achieve above task in multiple ways –

• Simple Approach
• Using User Input
• Using Lambda
• Using Function
• Using user defined Complex number using Class

Simple Approach

Multiplication operator (i.e. * operator) can be used to multiply two complex numbers. For example,

 
a = 30+4j
b = 15+2j
result = a * b
print("Result =", result)

Output:

 
Result = (442+120j)

Using User Input

In above example, two complex numbers were hardcoded values. We can take those complex numbers as input from user as well. For example,

 
a = complex(input("Enter first complex number: "))
b = complex(input("Enter second complex number: "))
result = a * b
print("Result =", result)

Output:

 
Enter first complex number: 
10+2j
Enter second complex number: 
1+4j
Result = (2+42j)

Using Lambda

We can also use lambda and * operator to multiply two complex numbers. For example,

 
if __name__ == "__main__" :
    num1 = 15+86j
    num2 = 14+32j
     
    # Multiply two complex numbers
    multiply_twoNum = lambda num1, num2 : num1 * num2
    print("Result =", multiply_twoNum(num1, num2))

Output:

 
Result = (-2542+1684j)

Using Function

We can write logic to multiply two complex numbers inside python function as well. For example,

 
def multiplyComplex(a, b):
    return a * b
 
print("Result =", multiplyComplex(20+2j, 10+12j))

Output:

 
Result = (176+260j)

Using user defined Complex number using Class

Writing logic to multiply two complex numbers is bit tricky when we have user defined complex number using class. For example,

 
class ComplexNumber():

    def init(self):
        self.real = int(input("Enter Real part: "))
        self.imaginary = int(input("Enter Imaginary part: "))

    def display(self):
        sign = "+" if(self.imaginary >= 0) else ""
        print(self.real, sign, self.imaginary, "j", sep="")

    def multiply(self, c1, c2):
        res = complex(c1.real, c1.imaginary) * complex(c1.real, c1.imaginary)
        self.real = res.real
        self.imaginary = res.imag


print("First complex number: ")
c1 = ComplexNumber()
c1.init()

print("Second complex number: ")
c2 = ComplexNumber()
c2.init()

print("Result = ")
c3 = ComplexNumber()
c3.multiply(c1, c2)
c3.display()

Output:

 
First complex number: 
Enter Real part: 
10
Enter Imaginary part: 
10
Second complex number: 
Enter Real part: 
20
Enter Imaginary part: 
20
Result = 
0.0+200.0j

That’s how we can write python program to multiply two complex numbers with examples.

Reference: Official Doc

Learn about more python examples at – https://tutorialwing.com/python-tutorial/