Method
NumCosmoMathLaurentSeriesjacobi_anger_reduce
Declaration [src]
gdouble
ncm_laurent_series_jacobi_anger_reduce (
const NcmLaurentSeries* cm,
gdouble phi,
const gdouble* Ik,
gint n_Ik
)
Description [src]
Exact reduction of
$\int_0^{2\pi} cm(\theta)\exp(z(\cos(\theta-\phi)-1))\,d\theta$
via the Jacobi-Anger identity, given cm‘s own harmonic content and
precomputed scaled Bessel values — no numerical quadrature over $\theta$
at all. Verified against direct numerical theta-integration
(test_ncm_laurent_series.c); note this includes the overall $2\pi$ factor
from the $\theta$-integral itself, so the return value is meaningful on
its own without relying on a caller-side normalization to supply it.