The three-term recursion for Chebyshev polynomials is mixed forward-backward stable

This paper provides an error analysis of the three-term recurrence relation (TTRR) T n+1(x)=2x T n (x)−T n−1(x) for the evaluation of the Chebyshev polynomial of the first kind T N (x) in the interval [−1,1]. We prove that the computed value of T N (x) from this recurrence is very close to the exact value of the Chebyshev polynomial T N of a slightly perturbed value of x. The lower and upper bounds for the function CN(x)=|TN(x)|+|xT′N(x)| are also derived. Numerical examples that illustrate our theoretical results are given.