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Margin — two-way (Power)

Two-way Power-method margin tools, paired on one page. Strip recovers fair Malay from a priced quote; Apply injects ladder MARGIN into a fair pair and snaps to the published 0.01 Malay grid. The two are inverses up to the 0.01-step snap. This is the same two-way strip the Odds Generation engine runs on the Handicap and Total quotes before it back-solves the goal rates; the multi-way analog uses the Shin model — see Margin — multi-way (Shin).

/ on a Malay side walks the 0.01 ladder and moves the partner the opposite way (Strip tab); Shift takes 10 steps.

Recover the fair Malay magnitude from a two-way priced market (HANDICAP / TOTAL / ODD_EVEN) via the Power method. The solver finds exponent x such that q₁^(1/x) + q₂^(1/x) = 1; fair probabilities pᵢ = qᵢ^(1/x) collapse to a single ±m fair pair because every fair two-way market has |m₁| = |m₂| = min(p₁,p₂)/max(p₁,p₂) in Malay. The signed assignment (which side is favorite) is reported alongside the magnitude. Production runs this as an O(1) precomputed lookup table; this demo solves it live via Newton iteration so the math is visible.

Worked example — balanced line, ladder MARGIN 0.08
Priced Malay (+0.96, +0.96) — implied (0.5102, 0.5102) — overround 1.0204
→ exponent x ≈ 0.9709 → fair (0.5000, 0.5000) → fair Malay ±1.0000
SIDE 1 = +1.0000, SIDE 2 = −1.0000 (even-money tiebreak goes to SIDE 1).
Press ↑/↓ on either side to slide the line — ladder MARGIN stays at 0.08.
Priced Malay (input)
SIDE 1 priced Malaym₁
Priced Malay quote on SIDE 1.
−1 ≤ m₁ ≤ +1, m₁ ≠ 0
SIDE 2 priced Malaym₂
Priced Malay quote on SIDE 2.
−1 ≤ m₂ ≤ +1, m₂ ≠ 0
Derived
OverroundQ
Q = q₁ + q₂ where qᵢ = 1/dᵢ and dᵢ is the decimal odds derived from mᵢ. Power-method-equivalent margin scalar m = 2 − 2/Q.
Exponentx
Solves q₁^(1/x) + q₂^(1/x) = 1 via Newton-Raphson. x = 1 means no margin to strip (Q would equal 1).
Fair Malay (output)
Fair Malay (±)m fair
Magnitude of the fair pair. Equals min(p₁, p₂) / max(p₁, p₂) by the Malay identity: favorite gets +m fair, underdog gets −m fair. The SIDE 1 / SIDE 2 assignment is reported below.
SIDE 1 / SIDE 2 sign±
Which side carries the + (favorite) and which the (underdog), determined by p₁ vs p₂ after the strip.