astropy/astropy — pull request #3074 by aconley (2014-11-05 21:30:30+00:00)
Title: More stringent default tolerance in cosmology.z_at_value.  Doc fixes

* Default tolerance decreased from 1e-5 to 1e-8 in z_at_value;
redshifts are occasionally measured to better than 1e-5, so it
makes sense to be more precise by default. 1e-8 seems like
enough for any practical usage. This follows the precise by
default, slow by express instruction principle.
* Change default zmin to a small but non-zero value in z_at_value
because some of the methods are not defined at z = 0 (like distmod).
* Fix example given in z_at_value docs, which used np.logspace
incorrectly (it assumed logspace worked the way it -should- work,
but sadly not the way it actually does).
* Increase stringency of roundtrip z_at_value test, add roundtrip
test of angular_diameter_distance_z1z2.
* Closes #3008