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gegenbauer(n, alpha, monic=False)

Defined to be the solution of

$$(1 - x^2)\frac{d^2}{dx^2}C_n^{(\alpha)} - (2\alpha + 1)x\frac{d}{dx}C_n^{(\alpha)} + n(n + 2\alpha)C_n^{(\alpha)} = 0$$

for $\alpha > -1/2$ ; $C_n^{(\alpha)}$ is a polynomial of degree $n$ .

Notes

The polynomials $C_n^{(\alpha)}$ are orthogonal over $[-1,1]$ with weight function $(1 - x^2)^{(\alpha - 1/2)}$ .

Parameters

n : int

Degree of the polynomial.

alpha : float

Parameter, must be greater than -0.5.

monic : bool, optional

If :None:None:`True`, scale the leading coefficient to be 1. Default is :None:None:`False`.

Returns

C : orthopoly1d

Gegenbauer polynomial.

Gegenbauer (ultraspherical) polynomial.

Examples

>>> from scipy import special
... import matplotlib.pyplot as plt

We can initialize a variable p as a Gegenbauer polynomial using the gegenbauer function and evaluate at a point x = 1 .

>>> p = special.gegenbauer(3, 0.5, monic=False)
... p poly1d([ 2.5, 0. , -1.5, 0. ])
>>> p(1)
1.0

To evaluate p at various points x in the interval (-3, 3) , simply pass an array x to p as follows:

>>> x = np.linspace(-3, 3, 400)
... y = p(x)

We can then visualize x, y using matplotlib.pyplot .

>>> fig, ax = plt.subplots()
... ax.plot(x, y)
... ax.set_title("Gegenbauer (ultraspherical) polynomial of degree 3")
... ax.set_xlabel("x")
... ax.set_ylabel("G_3(x)")
... plt.show()
See :

Back References

The following pages refer to to this document either explicitly or contain code examples using this.

scipy.special._orthogonal.gegenbauer

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GitHub : /scipy/special/_orthogonal.py#1504
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