quadint 0.0.11

A quadint class, for using quadratic integers.

quadint

Fast, integer-backed algebraic number types for exact arithmetic in imaginary quadratic integer rings.

• complexint: a Gaussian integer type that mirrors Python’s complex, but stores int components (no floating-point drift).
• QuadInt / QuadraticRing: a general quadratic-integer implementation for elements of the form
  $(a + b\sqrt{D}) / \mathrm{den}$ with $den ∈ {1,2}$.
• eisensteinint: Eisenstein integers in the ω-basis (a + bω, where ω = (-1 + √-3)/2).
• dualint: dual integers of the form a + bε where ε² = 0 and ε != 0 (useful for exact first-order / automatic-differentiation-style arithmetic).

Designed for discrete math, number theory tooling, and high-throughput exact computations (this project is built to compile cleanly with mypyc).

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Installation

python -m pip install quadint

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Quickstart (recommended): complexint

from quadint import complexint

a = complexint(1, 2)
b = complexint(3, 6)

c = a * b
print(c)          # "(-9+12j)"  (exact, integer-backed)
print(c.real)     # -9
print(c.imag)     # 12
print(type(c.real))  # <class 'int'>

print(abs(a))     # 1^2 + 2^2 = 5  (norm)

complexint is ideal when you want something that feels like complex, but with infinite-precision integer components.

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Quadratic integers: make_quadint

Create a ring instance for a chosen discriminant parameter D, then construct values in that ring:

from quadint import make_quadint

Q2 = make_quadint(-2)  # Z[√-2]

x = Q2(1, 2)           # (1 + 2*sqrt(-2))
y = Q2(3, 6)

print(x * y)           # "(-21+12*sqrt(-2))"
print(abs(x))          # norm: 1^2 - (-2)*2^2 = 9

Common operations include +, -, *, ** (non-negative powers), conjugate(), and abs() (the norm).

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Eisenstein integers: eisensteinint

from quadint.eisenstein import eisensteinint

z = eisensteinint(2, 3)   # 2 + 3ω
w = eisensteinint(1, -1)  # 1 - ω

print(z)
print(z * w)              # exact product in Z[ω]
print(abs(z))             # norm (integer)

Use real and omega to access the ω-basis components.

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Dual integers: dualint

from quadint import dualint

z = dualint(2, 3)   # 2 + 3ε
w = dualint(1, -1)  # 1 - ε

print(z)
print(z * w)              # (2+1ε)

Use real and dual (or epsilon) to access the ε-basis components.

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Division & interoperability notes

• This package is primarily intended for exact, discrete arithmetic (+, -, *, **, conjugation, norms).
• Some division helpers exist (e.g. divmod, //, %) for imaginary quadratic rings, using a nearest-lattice approach; it may be NotImplemented for D ≥ 0, and behavior depends on the ring being Euclidean enough for your use case.
• **Floats and Python complex are accepted in some operations but are converted via int(...), which truncates toward zero. If you care about rationals, avoid mixing in float.

Example of truncation behavior:

from quadint import complexint

a = complexint(3, 6)

print(a / 3)     # "(1+2j)"
print(a / 3.5)   # "(1+2j)"  (3.5 -> 3 by int(...) conversion)

print(a + 1)     # "(4+6j)"
print(a + 1.5)   # "(4+6j)"  (1.5 -> 1)

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Minimal API overview

Constructors

• complexint(a: int = 0, b: int = 0)
• eisensteinint(a: int = 0, b: int = 0) where a + bω
• make_quadint(D: int) -> QuadraticRing

Ring instance (QuadraticRing)

• Q(a: int = 0, b: int = 0) -> QuadInt (constructs using the ring’s internal basis)
• Q.from_ab(a: int, b: int) -> QuadInt (construct with user coords, respecting den)
• Q.from_obj(x) -> QuadInt (embed int/float, and complex only when D == -1)

Value type (QuadInt)

• x.conjugate()
• abs(x) (norm)
• divmod(x, y), x // y, x % y (where supported)
• Iteration/indexing over the stored coefficients: list(x), x[0], x[1]