wcosmo.wcosmo.z_at_value#

wcosmo.wcosmo.z_at_value(func, fval, zmin=0.0001, zmax=100, **kwargs)[source]#

Compute the redshift at which a function equals a given value.

This follows the approach in astropy’s z_at_value function closely, but uses linear interpolation instead of a root finder.

Parameters:

func: callable: The function to evaluate, e.g., Planck15.luminosity_distance, this should take fval as the only input.
fval: float | array-like: The value of the function at the desired redshift
zmin: float: The minimum redshift used in the conversion from distance to redshift, default=1e-4
zmax: float: The maximum redshift used in the conversion from distance to redshift, default=100

Returns: