Paste a list of numbers and see whether it fits an arithmetic, geometric, Fibonacci-like or polynomial rule, with the next term and the common difference or ratio — plus an honest note on how much a fit is actually worth.
At least 3 numbers. Results update as you type.
Arithmetic
Every gap is the same. Next term is the last one plus the common difference. A gap check is exact — there is nothing to solve, so a false positive is impossible.
Geometric
Every term is the previous one times a constant ratio. Fails if any term is zero (division by zero), so sequences containing 0 are not called geometric unless every term is 0.
Fibonacci-like
Fits aₙ = p·aₙ₋₁ + q·aₙ₋₂, solving for p and q from the first four terms and then checking every later term. Plain Fibonacci is the case p = q = 1. The tribonacci sequence 1, 1, 2, 4, 7, 13 is p = 1, q = 2 and is caught here too.
Polynomial
Fits aₙ = c₀ + c₁x + c₂x² + … by solving a Vandermonde system, starting at the lowest degree that reproduces every term exactly. Because n points always fit a degree n−1 polynomial, this is the weakest of the exact fits and is labelled as such.
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One input, fourteen cases: title, sentence, camelCase, PascalCase, kebab, snake, dot and more.
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