## Class `Distances`

Description:
  Functions for converting between different measures of cosmological distance.

  The following parameters are used:

  - z: redshift
  - H0: Hubble constant in km/sec/Mpc (example value ~70)
  - omegaM: Density ratio of the universe (example value 0.3)
  - omegaLambda: Normalised cosmological constant (example value 0.7)

  For a flat universe, `omegaM`+`omegaLambda`=1

  The terms and formulae used here are taken from the paper by D.W.Hogg, Distance measures in cosmology, astro-ph/9905116 v4 (2000).