Function builtin_bessel_j 

fn builtin_bessel_j(
    args: &[RValue],
    _: &[(String, RValue)],
) -> Result<RValue, RError>

Bessel function of the first kind, J_nu(x).

Computes J_nu(x) for integer order nu using libm’s jn function. R’s besselJ also supports non-integer nu, but this implementation currently handles integer orders only (non-integer orders return NaN with a warning).

@param x numeric vector @param nu numeric scalar (order, rounded to nearest integer) @return numeric vector of Bessel J values