Function
NumCosmoMathsf_sbessel_jl_deriv_from_array
Declaration [src]
gdouble
ncm_sf_sbessel_jl_deriv_from_array (
guint ell,
gdouble x,
const gdouble* jl_x
)
Description [src]
Computes $j_\ell’(x)$ from precomputed $j_l(x)$ values (such as those filled by ncm_sf_sbessel_array_eval()) using $j_\ell’(x) = j_{\ell-1}(x) - \frac{\ell+1}{x} j_\ell(x)$. The downward form keeps the required indices within $[0, \ell]$; its two terms agree to a factor of about two at small $x$, so no accuracy is lost to cancellation there. For $\ell = 0$ it returns $-j_1(x)$ evaluated directly.
This function is not directly available to language bindings.