lib.survey_selection.wide_angle.odd_wide_angle_coefficients

lib.survey_selection.wide_angle.odd_wide_angle_coefficients(ell, wa_order=1, los='firspoint')

Compute coefficients of odd wide-angle expansion, i.e.:

\[\frac{\ell \left(\ell - 1\right)}{2 \ell \left(2 \ell - 1\right)}, - \frac{\left(\ell + 1\right) \left(\ell + 2\right)}{2 \ell \left(2 \ell + 3\right)}\]

See https://fr.overleaf.com/read/hpgbwqzmtcxn. A minus sign is applied on both factors if los is ‘endpoint’.

Parameters

• ell (int) – Multipole order.

• wa_order (int, default=1) – Wide-angle expansion order. So far only order 1 is supported.

• los (string) –

  Choice of line-of-sight, either:

  • ’firstpoint’: the separation vector starts at the end of the line-of-sight

  • ’endpoint’: the separation vector ends at the end of the line-of-sight.

Returns

• ells (list) – List of multipole orders of correlation function.

• coeffs (list) – List of coefficients to apply to correlation function multipoles corresponding to output ells.