equation)的n次(英语:Degreeofapolynomial)代數方程式。只有線性齊次常系數的微分方程或差分方程才有特徵方程式。考慮一微分方程,其因变量為y,an, an − 1, ..., a1, a0為常数 a n y ( n ) + a n − 1 y ( n − 1 ) + ⋯ + a 1 y ′ + a
Ran; Safra, Shmuel, A sub-constant error-probability low-degree test, and a sub-constant error-probability PCP characterization of NP, Proc. STOC 1997: