Gaussian Integer Calculator

Arithmetic in Z[i]

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About Gaussian Integer Calculator

A Gaussian integer calculator for arithmetic in Z[i]. Computes addition, multiplication, norm N(a+bi)=a²+b², conjugate, division with remainder, and GCD. Checks primality in Z[i]. All calculations are client-side.

Gaussian Integer Calculator Features

  • Add/Multiply
  • Norm
  • Conjugate
  • GCD
  • Primality
Gaussian integers Z[i] = {a+bi : a,b∈Z}. Norm N(a+bi) = a²+b². Units: ±1, ±i. Gaussian prime: irreducible in Z[i]. A rational prime p: splits if p≡1(mod 4), stays prime if p≡3(mod 4), ramifies if p=2=(1+i)(1−i)(−i).

How to Use

Enter two Gaussian integers:

  • a+bi: First number
  • c+di: Second number
  • Operations: +, ×, norm, GCD

Gaussian Primes

π∈Z[i] is prime if N(π) is prime, OR π = p (rational prime with p≡3 mod 4). Example: 2+i is prime (N=5), 3 is prime in Z[i] (stays prime), but 5=(2+i)(2−i) splits.

Applications

  • Sums of two squares
  • Fermat's theorem on primes
  • Signal processing (QAM)
  • Algebraic number theory

Step-by-Step Instructions

  1. 1Enter a+bi.
  2. 2Enter c+di.
  3. 3Choose operation.
  4. 4View result.
  5. 5Check Gaussian primality.

Gaussian Integer Calculator — Frequently Asked Questions

Which integers are sums of two squares?+

n = a²+b² iff every prime factor p≡3(mod 4) appears to an even power in n. This follows from Gaussian integer factorization: N(z) = |z|² is a sum of two squares, and unique factorization in Z[i] governs which norms are achievable.

How does GCD work in Z[i]?+

Euclidean algorithm works because Z[i] is a Euclidean domain with norm N(a+bi)=a²+b². Division: z₁/z₂ rounded to nearest Gaussian integer gives quotient, remainder has smaller norm. Iterate until remainder is 0.

What is the fundamental theorem for Z[i]?+

Z[i] is a unique factorization domain (UFD). Every non-zero non-unit factors uniquely into Gaussian primes (up to units ±1,±i). This is analogous to the fundamental theorem of arithmetic but in Z[i].

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