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Inverted Lambda

A hybrid map that adds a rational quadratic term to the complex logistic recurrence, bringing movable poles into the orbit.

Open in Explorer
The Inverted Lambda fractal with dark lobes split by bright fault lines and knot-like structures
The Inverted Lambda parameter plane: logistic lobes interrupted by the rational correction, with seams and abrupt scale changes.

Overview

Inverted Lambda begins with the Lambda fractal’s logistic recurrence and adds a rational correction. The first term, c·z(1−z), is the standard complex logistic map. The second, 0.18/(z² + c), is reciprocal and quadratic; when its denominator approaches zero, it can hurl the orbit to very large values.

That fraction changes the rules. The plain logistic map is a polynomial, smooth everywhere; Inverted Lambda is a rational map with movable poles. An orbit can head toward infinity through unbounded growth, or by wandering too close to the divisor. The parent’s round lobes remain, but jagged seams, knot-like tangles, and sudden scale changes cut through them.

The 0.18 is fixed, not another parameter. It keeps the polynomial and rational contributions both active within a moderate number of iterations.

The Mathematics

Lambda-reciprocal iteration

z(n+1) = c z(n)(1 - z(n)) + 0.18 / (z(n)^2 + c)

Every step combines two contributions. First comes c·z(1−z), the quadratic logistic step behind the Lambda parameter set. Then comes a rational correction with fixed numerator 0.18 and denominator z² + c. A large denominator makes that correction small, so the map nearly follows the pure logistic version. Near z² + c = 0, it surges and may send the orbit far away.

Take c = 1 + i and start at z₀ = 0. The first term gives 1 × 0 × 1 = 0. The second term: 0.18 / (0 + (1+i)) = 0.18/(1+i) = 0.09 − 0.09i. So z₁ ≈ 0.09 − 0.09i: a small nudge away from the logistic baseline. On later steps the rational term keeps steering, creating paths unavailable to the pure logistic family. The denominator z² + c marks the poles—near-singular values—and their positions move with c.

History

Inverted Lambda is a hybrid construction joining two well-studied complex-dynamics families. Its logistic base comes from the lambda fractal tradition studied by Mandelbrot (1980). Adding a reciprocal quadratic term to a polynomial map relates to singular perturbation, which Curt McMullen explored in the late 1980s for rational maps zⁿ + λ/zⁿ.

This particular pairing—a logistic map and a reciprocal quadratic with a fixed constant numerator—appears to be a novel fractal-rendering formulation. It does not trace to one historical paper; it draws on ideas developed across decades of complex-dynamics research. “Inverted Lambda” describes the construction rather than a term from the research literature.

Visual Characteristics

The parameter plane keeps the logistic family’s rounded lobes, but sharp seams, dense knots, and patches where color suddenly deepens or brightens interrupt them. Near a pole, an orbit makes a large jump, and the escape-time coloring records that break.

It can resemble a smooth surface cracked from within. Far from the poles, the parent Lambda structure is still legible; the rational correction draws angular, crystalline detail across it.

Remix and Examples

Start from the canonical Document

Open the same approved formula state used by this guide, then change the view, coloring, transforms, or animation in the interactive Explorer.

Frequently Asked Questions

What is inverted in this formula?

“Inverted” names the reciprocal term added to the logistic recurrence. It is not a geometric flip of the image or a reflection of the parameter plane. The reciprocal quadratic term 1/(z² + c) is the inversion meant here.

Where can poles occur?

A pole occurs wherever the denominator z² + c is zero — that is, when z = ±√(−c). Since c is free, pole locations depend on the parameter being explored. An evolving orbit may pass close to one, making the rational term spike and the trajectory jump far away.

References