SL(2,ℝ) (Thurston)

Shear flow, geodesic divergence, rotation-shear coupling
symmetrydim 35 metrics

What It Measures

The character of 2x2 matrix dynamics — whether the accumulated transformation rotates, shears, or stretches.

Converts each byte triple to an SL(2,R) matrix via the KAK decomposition: a rotation, a hyperbolic boost, and a second rotation. These three parameters span all three conjugacy classes of 2x2 matrices with determinant 1. The geometry classifies each matrix by its trace: elliptic (|trace| < 2, rotation-dominated), parabolic (|trace| = 2, shear), or hyperbolic (|trace| > 2, exponential stretch). A running product of matrices accumulates the signal's overall dynamical character.

Metrics

hyperbolic_fraction

Fraction of matrices with |trace| > 2. L-System Dragon, pulse-width modulation, and Morse code all score 1.0 (every matrix is hyperbolic — their binary structure pushes the boost parameter to extreme values). Earthquake P-wave scores 0.014 (almost entirely elliptic — the smooth waveform creates small boosts). This separates signals with discontinuous jumps (hyperbolic) from smooth oscillations (elliptic).

lyapunov_exponent

Average rate of exponential growth in the running matrix product, computed over blocks of 50 matrices. Rainfall (1.98) and Collatz gap lengths (1.96) score highest — their bursty or irregular dynamics create matrices whose product grows rapidly. Earthquake P-wave (0.020) is the lowest non-degenerate value: its smooth oscillation produces near-identity matrices that barely grow. This is a genuine Lyapunov exponent of the matrix cocycle, not an ad-hoc estimate.

mean_trace

Average trace of all matrices. L-System Dragon, Morse code, and Rule 110 all score 7.52 (far into the hyperbolic regime). DNA sequences score around -2.6 (elliptic regime with negative trace — the base pair frequencies create matrices with trace near the elliptic boundary). Logistic period-3 scores -2.77 (deepest into the negative-trace elliptic region). The sign of mean_trace separates two flavors of rotational dynamics: positive trace means the rotations partially cancel; negative means they compound.

parabolic_fraction

Fraction of matrices near the elliptic/hyperbolic boundary (|trace²-4| <= 0.2). Ambient microseism (0.40) and bearing inner fault (0.39) score highest — their narrowband oscillations produce matrices that hover near the boundary. This is the rarest conjugacy class: most data is either clearly elliptic or clearly hyperbolic, with few matrices landing in the thin parabolic strip. High parabolic fraction signals a critical or transitional dynamical regime.

Atlas Rankings

hyperbolic_fraction
SourceDomainValue
L-System (Dragon Curve)exotic1.0000
Pulse-Width Modulationwaveform1.0000
Morse Codewaveform1.0000
···
Constant 0xFFnoise0.0000
Constant 0x00noise0.0000
Earthquake P-wavegeophysics0.0145
lyapunov_exponent
SourceDomainValue
Rainfall (ORD Hourly)climate1.9826
Collatz Gap Lengthsnumber_theory1.9627
Forest Fireexotic1.8872
···
Constant 0xFFnoise0.0000
Constant 0x00noise0.0000
Earthquake P-wavegeophysics0.0203
mean_spectral_radius
SourceDomainValue
L-System (Dragon Curve)exotic7.3891
Morse Codewaveform7.3891
Rule 110exotic7.3891
···
Constant 0xFFnoise0.0000
Constant 0x00noise0.0000
Earthquake P-wavegeophysics1.0199
mean_trace
SourceDomainValue
L-System (Dragon Curve)exotic7.5244
Morse Codewaveform7.5244
Rule 110exotic7.5244
···
Logistic r=3.83 (Period-3 Window)chaos-2.7732
DNA Thermusbio-2.6348
DNA Chimpbio-2.5393
parabolic_fraction
SourceDomainValue
Ambient Microseismgeophysics0.3969
Bearing Innerbearing0.3878
Devil's Staircaseexotic0.3444
···
Constant 0xFFnoise0.0000
Constant 0x00noise0.0000
Logistic r=3.5 (Period-4)chaos0.0000

When It Lights Up

SL(2,R) is the most algebraically rich Thurston geometry in the framework. Its conjugacy class decomposition (elliptic/parabolic/hyperbolic) provides a three-way classification that no other metric replicates. In the symmetry view, hyperbolic_fraction is the primary separator: it cleanly divides binary/symbolic sources (fraction near 1.0) from smooth continuous signals (fraction near 0). The lyapunov_exponent adds a growth-rate axis, and mean_trace adds a polarity axis. Together they place each source in a 3D space where binary chaos, smooth oscillation, and critical behavior occupy distinct regions.

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