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Polynomial

A polynomial is a linear combination of powers of a variable (e.g., ax²+bx+c), supporting addition, subtraction, multiplication, division, differentiation, and integration; it is the foundation of algebra and numerical computing.

Purpose

To represent and manipulate algebraic expressions, the basis of interpolation, approximation, and equation solving.

Mechanism

P(x)=a_n×x^n+...+a_1×x+a_0. The degree is the highest power. Addition and subtraction work coefficient-wise; multiplication convolves coefficients. Evaluation uses Horner's method in O(n). Root finding: closed formulas for low degrees, Newton iteration for high degrees. FFT accelerates polynomial multiplication to O(n log n).

Use cases

  • Curve fitting and interpolation
  • Error-correcting codes (Reed-Solomon)
  • CRC generator polynomials
  • Numerical approximation

Examples

  • Input
    2x²+3x+1 at x=2
    Output
    2×4+3×2+1=15

    Horner evaluation

Common errors

High-degree polynomials are numerically unstable
Use orthogonal polynomials or center the variable

Related terms

Related tools

References