scipy.special.jnyn_zeros

scipy.special.jnyn_zeros(n, nt)[source]

Compute nt zeros of Bessel functions Jn(x), Jn’(x), Yn(x), and Yn’(x).

Returns 4 arrays of length nt, corresponding to the first nt zeros of Jn(x), Jn’(x), Yn(x), and Yn’(x), respectively. The zeros are returned in ascending order.

Parameters
nint

Order of the Bessel functions

ntint

Number (<=1200) of zeros to compute

Returns
Jnndarray

First nt zeros of Jn

Jnpndarray

First nt zeros of Jn’

Ynndarray

First nt zeros of Yn

Ynpndarray

First nt zeros of Yn’

References

1

Zhang, Shanjie and Jin, Jianming. “Computation of Special Functions”, John Wiley and Sons, 1996, chapter 5. https://people.sc.fsu.edu/~jburkardt/f77_src/special_functions/special_functions.html

Examples

Compute the first three roots of \(J_1\), \(J_1'\), \(Y_1\) and \(Y_1'\).

>>> from scipy.special import jnyn_zeros
>>> jn_roots, jnp_roots, yn_roots, ynp_roots = jnyn_zeros(1, 3)
>>> jn_roots, yn_roots
(array([ 3.83170597,  7.01558667, 10.17346814]),
 array([2.19714133, 5.42968104, 8.59600587]))

Plot \(J_1\), \(J_1'\), \(Y_1\), \(Y_1'\) and their roots.

>>> import numpy as np
>>> import matplotlib.pyplot as plt
>>> from scipy.special import jnyn_zeros, jvp, jn, yvp, yn
>>> jn_roots, jnp_roots, yn_roots, ynp_roots = jnyn_zeros(1, 3)
>>> fig, ax = plt.subplots()
>>> xmax= 11
>>> x = np.linspace(0, xmax)
>>> ax.plot(x, jn(1, x), label=r"$J_1$", c='r')
>>> ax.plot(x, jvp(1, x, 1), label=r"$J_1'$", c='b')
>>> ax.plot(x, yn(1, x), label=r"$Y_1$", c='y')
>>> ax.plot(x, yvp(1, x, 1), label=r"$Y_1'$", c='c')
>>> zeros = np.zeros((3, ))
>>> ax.scatter(jn_roots, zeros, s=30, c='r', zorder=5,
...            label=r"$J_1$ roots")
>>> ax.scatter(jnp_roots, zeros, s=30, c='b', zorder=5,
...            label=r"$J_1'$ roots")
>>> ax.scatter(yn_roots, zeros, s=30, c='y', zorder=5,
...            label=r"$Y_1$ roots")
>>> ax.scatter(ynp_roots, zeros, s=30, c='c', zorder=5,
...            label=r"$Y_1'$ roots")
>>> ax.hlines(0, 0, xmax, color='k')
>>> ax.set_ylim(-0.6, 0.6)
>>> ax.set_xlim(0, xmax)
>>> ax.legend(ncol=2, bbox_to_anchor=(1., 0.75))
>>> plt.tight_layout()
>>> plt.show()
../../_images/scipy-special-jnyn_zeros-1.png