Complex Number Calculator

Perform arithmetic operations with complex numbers in rectangular and polar forms

Complex Number Operations

Enter two complex numbers in the form a + bi to perform various operations:

First Complex Number (z₁)

z₁ = 3 + 4i

Polar: 5 ∠ 53.130102°

Second Complex Number (z₂)

z₂ = 1 + 2i

Polar: 2.236068 ∠ 63.434949°

Results

Addition (z₁ + z₂)

4 + 6i
7.211103 ∠ 56.309932°

Subtraction (z₁ - z₂)

2 + 2i
2.828427 ∠ 45°

Multiplication (z₁ × z₂)

-5 + 10i
11.18034 ∠ 116.565051°

Division (z₁ ÷ z₂)

2.2 - 0.4i
2.236068 ∠ -10.304846°

Power (z₁^z₂)

-0.419813 - 0.660452i

ln(z₁)

1.609438 + 0.927295i

√z₁

2 + i

Conjugate z₁̄

3 - 4i

Conjugate z₂̄

1 - 2i

Step-by-Step Solutions

Addition

Add corresponding real and imaginary parts:

(3 + 4i) + (1 + 2i)
= (3 + 1) + (4 + 2)i
= 4 + 6i

Subtraction

Subtract corresponding real and imaginary parts:

(3 + 4i) - (1 + 2i)
= (3 - 1) + (4 - 2)i
= 2 + 2i

Multiplication

Use FOIL method: (a+bi)(c+di) = ac + adi + bci + bdi²:

(3 + 4i) × (1 + 2i)
= (3×1 - 4×2) + (3×2 + 4×1)i
= -5 + 10i

Division

Multiply by conjugate of denominator:

(3 + 4i) ÷ (1 + 2i)
= [(3×1 + 4×2) + (4×1 - 3×2)i] ÷ 5
= 2.2 - 0.4i

Complex Number Properties

Modulus Property

The modulus of a product equals the product of moduli

|z₁ × z₂| = |z₁| × |z₂|

Verification: 11.180340 = 11.180340

Conjugate Product

A complex number times its conjugate gives a real number

z × z̄ = |z|²

Verification: 3 + 4i × 3 - 4i = 25.000000

Polar Multiplication

In polar form, multiply moduli and add arguments

(r₁∠θ₁) × (r₂∠θ₂) = (r₁r₂)∠(θ₁+θ₂)

Verification: 11.18 ∠ 116.57°

Example Problems

Example 1

z₁ = 3 + 4i, z₂ = 1 + 2i
Addition: 4 + 6i
Multiplication: -5 + 10i
|z₁|: 5, |z₂|: √5 ≈ 2.236

Example 2

z₁ = 2 - 3i, z₂ = 4 + i
Addition: 6 - 2i
Multiplication: 11 - 10i
Division: 0.294 - 0.824i

Example 3

z₁ = i, z₂ = 1
Addition: 1 + i
Power z₁²: -1
Conjugate z₁̄: -i

Example 4

z₁ = 1 + i, z₂ = 1 - i
Multiplication: 2 (real result)
Note: Conjugate pairs multiply to real

Quick Reference

Standard Form
z = a + bi
Polar Form
z = r∠θ = r(cos θ + i sin θ)
Modulus
|z| = √(a² + b²)
Argument
θ = arctan(b/a)

Operation Formulas

Addition
(a+bi) + (c+di) = (a+c) + (b+d)i
Subtraction
(a+bi) - (c+di) = (a-c) + (b-d)i
Multiplication
(a+bi)(c+di) = (ac-bd) + (ad+bc)i
Division
Multiply by conjugate of denominator

Polar Form Operations

Multiplication: multiply moduli, add arguments

Division: divide moduli, subtract arguments

Powers: raise modulus to power, multiply argument

Roots: take nth root of modulus, divide argument by n

Applications

Electrical Engineering
AC circuit analysis, impedance
Signal Processing
Fourier transforms, filters
Quantum Mechanics
Wave functions, probability
Computer Graphics
Rotations, transformations

Understanding Complex Numbers

What are Complex Numbers?

Complex numbers extend the real number system by introducing the imaginary unit i, where i² = -1. A complex number z = a + bi consists of a real part (a) and an imaginary part (b), enabling solutions to equations like x² + 1 = 0.

Rectangular vs. Polar Form

Complex numbers can be represented in rectangular form (a + bi) or polar form (r∠θ). The polar form is particularly useful for multiplication, division, and exponentiation, as these operations become simpler when working with magnitudes and angles.

Complex Plane Visualization

Complex numbers can be visualized on the complex plane, where the x-axis represents the real part and the y-axis represents the imaginary part. This geometric interpretation helps understand operations like addition (vector addition) and multiplication (rotation and scaling).

Key Properties

Conjugate Properties

  • • z · z̄ = |z|² (always real and non-negative)
  • • (z₁ + z₂)̄ = z̄₁ + z̄₂
  • • (z₁ · z₂)̄ = z̄₁ · z̄₂

Modulus Properties

  • • |z₁ · z₂| = |z₁| · |z₂|
  • • |z₁/z₂| = |z₁|/|z₂|
  • • |z₁ + z₂| ≤ |z₁| + |z₂| (triangle inequality)

Euler's Formula

e^(iθ) = cos θ + i sin θ
This connects complex exponentials with trigonometric functions.

Real-World Applications

AC Electrical Circuits

Complex numbers represent AC voltages and currents, where the real part represents the resistive component and the imaginary part represents the reactive component.

Signal Processing

The Fourier transform uses complex numbers to analyze frequency components of signals, enabling applications in audio processing, image compression, and communications.

Quantum Mechanics

Wave functions in quantum mechanics are complex-valued, and the squared magnitude gives the probability density of finding particles in specific states.