26 Numerics library [numerics]
26.9 Mathematical functions for floating-point types [c.math]
26.9.5 Mathematical special functions [sf.cmath]
26.9.5.8 Cylindrical Bessel functions (of the first kind) [sf.cmath.cyl_bessel_j]
double cyl_bessel_j(double nu, double x);
float cyl_bessel_jf(float nu, float x);
long double cyl_bessel_jl(long double nu, long double x);
Effects: These functions compute the cylindrical Bessel functions of the first kind of their respective arguments nu and x.
Returns:
![\[%
\mathsf{J}_\nu(x) =
\sum_{k=0}^\infty \frac{(-1)^k (x/2)^{\nu+2k}}
{k! \: \Gamma(\nu+k+1)},
\quad \mbox{for $x \ge 0$}
\]](math/8092557911366403652.png)
where
nu is nu and
x is x.