set the cosmology

Set the cosmology used (i.e., $H_0$, $q_0$, and $\Lambda_0$).

Syntax: cosmo <$H_0$><$q_0$><$\Lambda_0$>

where <$H_0$> is the Hubble constant in km/s/Mpc, <$q_0$> is the deceleration parameter, and <$\Lambda_0$> is the cosmological constant. If the cosmological constant is non-zero then at present XSPEC requires that the universe is flat. In this case the value of <$q_0$> will be ignored and XSPEC will assume that $\Omega_{matter}\geq 1-\Lambda_0$. The default values are <$H_0$> = 70, <$q_0$> = 0.0, and <$\Lambda_0$> = 0.73


XSPEC12>cosmo 100
// Set <$H_0$>= 100 km/s/Mpc
XSPEC12>cosmo ,0
// Set <$q_0$>= 0
XSPEC12>cosmo ,,0.7
// Set a flat universe with <$\Lambda_0$>= 0.7