scipy.special.eval_chebys#
- scipy.special.eval_chebys(n, x, out=None) = <ufunc 'eval_chebys'>#
- Evaluate Chebyshev polynomial of the second kind on [-2, 2] at a point. - These polynomials are defined as \[S_n(x) = U_n(x/2)\]- where \(U_n\) is a Chebyshev polynomial of the second kind. See 22.5.13 in [AS] for details. - Parameters:
- narray_like
- Degree of the polynomial. If not an integer, the result is determined via the relation to - eval_chebyu.
- xarray_like
- Points at which to evaluate the Chebyshev polynomial 
- outndarray, optional
- Optional output array for the function values 
 
- Returns:
- Sscalar or ndarray
- Values of the Chebyshev polynomial 
 
 - See also - roots_chebys
- roots and quadrature weights of Chebyshev polynomials of the second kind on [-2, 2] 
- chebys
- Chebyshev polynomial object 
- eval_chebyu
- evaluate Chebyshev polynomials of the second kind 
 - References [AS]- Milton Abramowitz and Irene A. Stegun, eds. Handbook of Mathematical Functions with Formulas, Graphs, and Mathematical Tables. New York: Dover, 1972. - Examples - >>> import numpy as np >>> import scipy.special as sc - They are a scaled version of the Chebyshev polynomials of the second kind. - >>> x = np.linspace(-2, 2, 6) >>> sc.eval_chebys(3, x) array([-4. , 0.672, 0.736, -0.736, -0.672, 4. ]) >>> sc.eval_chebyu(3, x / 2) array([-4. , 0.672, 0.736, -0.736, -0.672, 4. ])