# scipy.special.airy¶

scipy.special.airy(z) = <ufunc 'airy'>

Airy functions and their derivatives.

Parameters: z : array_like Real or complex argument. Ai, Aip, Bi, Bip : ndarrays Airy functions Ai and Bi, and their derivatives Aip and Bip.

airye
exponentially scaled Airy functions.

Notes

The Airy functions Ai and Bi are two independent solutions of

$y''(x) = x y(x).$

For real z in [-10, 10], the computation is carried out by calling the Cephes [1] airy routine, which uses power series summation for small z and rational minimax approximations for large z.

Outside this range, the AMOS [2] zairy and zbiry routines are employed. They are computed using power series for $$|z| < 1$$ and the following relations to modified Bessel functions for larger z (where $$t \equiv 2 z^{3/2}/3$$):

\begin{align}\begin{aligned}Ai(z) = \frac{1}{\pi \sqrt{3}} K_{1/3}(t)\\Ai'(z) = -\frac{z}{\pi \sqrt{3}} K_{2/3}(t)\\Bi(z) = \sqrt{\frac{z}{3}} \left(I_{-1/3}(t) + I_{1/3}(t) \right)\\Bi'(z) = \frac{z}{\sqrt{3}} \left(I_{-2/3}(t) + I_{2/3}(t)\right)\end{aligned}\end{align}

References

 [1] (1, 2) Cephes Mathematical Functions Library, http://www.netlib.org/cephes/index.html
 [2] (1, 2) Donald E. Amos, “AMOS, A Portable Package for Bessel Functions of a Complex Argument and Nonnegative Order”, http://netlib.org/amos/

Examples

Compute the Airy functions on the interval [-15, 5].

>>> from scipy import special
>>> x = np.linspace(-15, 5, 201)
>>> ai, aip, bi, bip = special.airy(x)


Plot Ai(x) and Bi(x).

>>> import matplotlib.pyplot as plt
>>> plt.plot(x, ai, 'r', label='Ai(x)')
>>> plt.plot(x, bi, 'b--', label='Bi(x)')
>>> plt.ylim(-0.5, 1.0)
>>> plt.grid()
>>> plt.legend(loc='upper left')
>>> plt.show()


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