If the first parameter is a non-negative integer, the ChebyshevT(n, x) function computes the nth Chebyshev polynomial of the first kind evaluated at x.

These polynomials are orthogonal on the interval (-1, 1) with respect to the weight function . These polynomials satisfy the following:

Chebyshev polynomials of the first kind satisfy the following recurrence relation:

where ChebyshevT(0,x) = 1 and ChebyshevT(1,x) = x.

This definition is analytically extended for arbitrary values of the first argument by