airyAi¶
Evaluates the Airy function.
Synopsis¶
airyAi (x)
Required Arguments¶
- float
x
(Input) - Argument for which the function value is desired.
Return Value¶
The Airy function evaluated at x, Ai(x).
Description¶
The airy function Ai(x) is defined to be
\[Ai(x) = \tfrac{1}{\pi} \int_0^{\infty} \cos \left(xt + \tfrac{1}{3} t^3\right) dt =
\sqrt{\frac{x}{3\pi^2}} K_{1/3} \left(\tfrac{2}{3} x^{3/2}\right)\]
The Bessel function \(K_v(x)\) is defined in besselExpK0.
If \(x<-1.31 \varepsilon^{-2/3}\), then the answer will have no precision. If \(x<-1.31 \varepsilon^{-1/3}\), the answer will be less accurate than half precision. Here ɛ = machine(4) is the machine precision.
Finally, x should be less than \(x_{max}\) so the answer does not underflow. Very approximately, \(x_{max}=\{-1.5 \ln s \}^{2/3}\), where s = machine(1), the smallest representable positive number.
For more information, see the description for machine.