scipy.special.jve¶
-
scipy.special.jve(v, z) = <ufunc 'jve'>¶ Exponentially scaled Bessel function of order v.
Defined as:
jve(v, z) = jv(v, z) * exp(-abs(z.imag))
- Parameters
- varray_like
Order (float).
- zarray_like
Argument (float or complex).
- Returns
- Jndarray
Value of the exponentially scaled Bessel function.
Notes
For positive v values, the computation is carried out using the AMOS [1] zbesj routine, which exploits the connection to the modified Bessel function \(I_v\),
\[ \begin{align}\begin{aligned}J_v(z) = \exp(v\pi\imath/2) I_v(-\imath z)\qquad (\Im z > 0)\\J_v(z) = \exp(-v\pi\imath/2) I_v(\imath z)\qquad (\Im z < 0)\end{aligned}\end{align} \]For negative v values the formula,
\[J_{-v}(z) = J_v(z) \cos(\pi v) - Y_v(z) \sin(\pi v)\]is used, where \(Y_v(z)\) is the Bessel function of the second kind, computed using the AMOS routine zbesy. Note that the second term is exactly zero for integer v; to improve accuracy the second term is explicitly omitted for v values such that v = floor(v).
References
- 1
Donald E. Amos, “AMOS, A Portable Package for Bessel Functions of a Complex Argument and Nonnegative Order”, http://netlib.org/amos/