Set the cosmology used (i.e., 
).
Syntax: cosmo 
where 
is the Hubble
constant in km s–1 Mpc–1, 
is
the deceleration parameter, and 
is
the cosmological constant. If the cosmological constant is non-zerothen at
present XSPEC requires that the universe is flat. In this case the value of 
will
be ignored and XSPEC will assume that 
. The default values are 
, 
,
and 
Examples:
XSPEC12> cosmo 100
// Set 
XSPEC12> cosmo ,0
// Set 
XSPEC12> cosmo ,,0.7
// Set a flat universe with 