calc_cos_gamma

luminet.black_hole_math.calc_cos_gamma(alpha: float, incl: float) → float

Calculate \(\cos(\gamma)\)

This is used in the argument of the Jacobi elliptic integrals.

\[\cos(\gamma) = \frac{\cos(\alpha)}{\sqrt{\cos(\alpha)^2 + \frac{1}{\tan(\theta_0)^2}}}\]

Parameters:

• alpha (float) – Angle in the black hole frame

• incl (float) – Inclination of the observer \(\theta_0\)

Returns:

float – \(\cos(\gamma)\)