About this calculator
How to convert between different representations of complex numbers? There are two commonly used representations of complex numbers: rectangular coordinate form (algebraic form) z = a + bi, and polar coordinate form (trigonometric form) z = r(cosθ + i sinθ) = r∠θ. Where a is the real part, b is the imaginary part, r is the module (|z| = √(a²+b²)), and θ is the argument (arg(z) = arctan(b/a)).
Both forms have their advantages. The rectangular coordinate form facilitates addition and subtraction operations: (a+bi) + (c+di) = (a+c) + (b+d)i. The polar form facilitates multiplication and division operations: r₁∠θ₁ × r₂∠θ₂ = r₁r₂∠(θ₁+θ₂). Euler's formula e^(iθ) = cosθ + i sinθ connects the two forms, and the polar coordinate form can also be written as z = re^(iθ).
In practical applications, form conversion is very common. In signal processing, the results of the Fourier transform represent amplitude and phase in polar coordinate form. In circuit analysis, the impedance of alternating current is represented by complex numbers, and the amplitude and phase difference are visually displayed in polar coordinate form. In control theory, the frequency response of a system is represented by a Bode diagram in the form of polar coordinates. In quantum mechanics, the phase of a wave function is described in polar form.
Our complex form conversion calculator quickly converts between rectangular and polar coordinates. Supports both angle and radian units, and automatically handles the main value range of the argument. Detailed conversion formulas and calculation steps are provided to help you understand the relationship between the two forms. Whether students are learning complex number theory or engineers are performing signal analysis, this tool can provide accurate and convenient conversion services.
What it calculates
The complex form converter changes a complex number between algebraic form a + bi, polar form r∠θ, and exponential form re^{iθ}.
Formula
- r = sqrt(a^2 + b^2)
- θ = atan2(b, a)
- a = r cos θ
- b = r sin θ
- re^{iθ} = r(cos θ + i sin θ)
Inputs
- Algebraic form: enter real part a and imaginary part b.
- Polar form: enter modulus r and angle θ.
- Use the same angle unit as the page setting.
Example
| Algebraic form | Polar form | Note |
|---|---|---|
| 1 + i | sqrt(2)∠45° | First quadrant |
| -1 + i | sqrt(2)∠135° | Second quadrant |
| 0 - 2i | 2∠-90° | Negative imaginary axis |
How to interpret the result
Algebraic form is convenient for addition and subtraction; polar and exponential forms are better for multiplication, division, powers, and roots. All forms describe the same point.
Common mistakes
- Do not mix degrees and radians.
- Keep quadrant information when computing θ.
- The modulus r cannot be negative.
How to use
Using the plural form conversion calculator is very simple. Just select the input form and enter the parameters.
**Method 1: Convert Cartesian coordinates to polar coordinates** 1. Select the "Rectangular coordinate" input mode 2. Enter the real part a and the imaginary part b 3. Click the "Convert" button 4. Look at the modulus r and the argument θ (angle or radians)
**Example 1:** Convert 3+4i to polar form. r = √(3²+4²) = √25 = 5. θ = arctan(4/3) ≈ 53.13° ≈ 0.927 radians. Result: 5∠53.13° or 5e^(0.927i).
**Example 2:** Convert -1+i to polar coordinate form. r = √((-1)²+1²) = √2 ≈ 1.414. θ = arctan(1/(-1)) = 135° (second quadrant) ≈ 2.356 radians. Result: √2∠135°.
**Method 2: Convert polar coordinates to rectangular coordinates** 1. Select "Polar Coordinates" input mode 2. Enter the modulus r and argument angle θ (select angle or radians) 3. Click the "Convert" button 4. Check the real part a and the imaginary part b
**Example 3:** Convert 2∠60° to Cartesian coordinate form. a = 2cos60° = 2×0.5 = 1. b = 2sin60° = 2×(√3/2) = √3 ≈ 1.732. Result: 1 + 1.732i.
**Example 4:** Convert e^(iπ) to rectangular coordinate form. r=1, θ=π. a = cos(π) = -1, b = sin(π) = 0. Result: -1 (Euler's identity: e^(iπ) = -1).
The calculator shows detailed conversion formulas, calculation steps and a comparison of the two forms.
Main features
• Bidirectional conversion: Cartesian coordinates ↔ polar coordinates • Angle unit: Supports angles and radians • Principal value of argument: automatically calculates the principal value of argument (-π to π or 0 to 2π) • Quadrant judgment: automatically judge the quadrant of a complex number • Euler form: displays the form of e^(iθ) • Conversion formula: display detailed conversion formula • Calculation steps: display the complete calculation process • Graphical presentation: plotting complex numbers in the complex plane • Batch conversion: supports batch conversion of multiple complex numbers • Totally free: no registration required, use anytime
Use cases
• Complex Number Analysis: Students learn the different representations of complex numbers • Signal processing: amplitude and phase representation of Fourier transform results • Circuit Analysis: Polar representation of impedance in AC circuits • Control theory: Bode plot of system frequency response • Quantum Mechanics: Amplitude and Phase of Wave Functions • Engineering calculations: formal conversions in complex number operations • Math Contest: Quickly convert plural forms • Exam Prep: Verify Answers to Plural Conversion Questions • Teaching aid: teacher explains the geometric meaning of complex numbers • Scientific Computing: Formal Choice in Complex Number-Intensive Computations