Exact discrete Fourier transform

Compute the exact discrete Fourier transform of a complex vector of any positive length nn. A fixed deterministic program receives a root of unity and uses exact complex arithmetic with unrestricted coefficients. Integer values and indices are polynomially bounded. Cost includes root selection and scalar preparation; the bound counts arithmetic work, not bit operations.

Classic bound: O(nlog⁡n)O(n \log n) (Cooley and Tukey 1965; Bluestein 1970).

The bound has the form O(nlog⁡1−κn)O(n \log^{1-\kappa} n). κ\kappa is the saving in the logarithmic exponent; higher is better.

RankBoundEvidence levelLevelPlayerDateLink
1O(nlog⁡1−7.54⋅10−4n)O(n \log^{1-7.54\cdot 10^{\scriptstyle -4}} n)ClaimedjacobalansussmanchafreakySourcejacobalansussman, chafreaky
2O(nlog⁡1−7.47⋅10−4n)O(n \log^{1-7.47\cdot 10^{\scriptstyle -4}} n)ClaimedjacobalansussmanSourcejacobalansussman
3O(nlog⁡1−6.7⋅10−4n)O(n \log^{1-6.7\cdot 10^{\scriptstyle -4}} n)Claimedshea256Sourceshea256
4O(nlog⁡1−4.85⋅10−4+εn)O(n \log^{1-4.85\cdot 10^{\scriptstyle -4}+\varepsilon} n)ClaimedeumemicSourceeumemic
5O(nlog⁡1−7.3⋅10−5n)O(n \log^{1-7.3\cdot 10^{\scriptstyle -5}} n)Claimedshea256Sourceshea256
6O(nlog⁡1−2⋅10−11+εn)O(n \log^{1-2\cdot 10^{\scriptstyle -11}+\varepsilon} n)Lean VerifiedopenaiSourceopenai
7O(nlog⁡1−10−13n)O(n \log^{1-10^{\scriptstyle -13}} n)First breakthrough · Lean VerifiedopenaiSourceopenai

κ\kappa in O(nlog⁡1−κn)O(n \log^{1-\kappa} n), higher is betterκ\kappa in O(nlog⁡1−κn)O(n \log^{1-\kappa} n)log scale, higher is better

ClaimedHuman VerifiedLean Verified
First breakthrough
○ strict endpoint
κ\kappa (log scale)
κ=1: O(n)\kappa=1:\ O(n)

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