C10a3: Real argument, real order

s17alc	nag_bessel_zeros Zeros of Bessel functions J_α(x), J'_α(x), Y_α(x) or Y'_α(x)
s18ekc	nag_bessel_j_alpha Bessel functions J_{α +n-1} (x) or J_{α -n+1} (x) for real x ≠ 0, non-negative α < 1 and n = 1,2,...,\|N\|+1