pub fn tsfn(phi: f64, sinphi: f64, e: f64) -> f64Expand description
Determine function ts(phi) defined in Snyder (1987), Eq. (7-10) Inputs: phi = geographic latitude (radians) e = eccentricity of the ellipsoid (dimensionless) Output: ts = exp(-psi) where psi is the isometric latitude (dimensionless) = 1 / (tan(chi) + sec(chi)) Here isometric latitude is defined by psi = log( tan(pi/4 + phi/2) * ( (1 - esin(phi)) / (1 + esin(phi)) )^(e/2) ) = asinh(tan(phi)) - e * atanh(e * sin(phi)) = asinh(tan(chi)) chi = conformal latitude