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- Astropy v5.2.1 »
- Cosmological Calculations (`astropy.cosmology`) »
- FlatFLRWMixin

# FlatFLRWMixin

class astropy.cosmology.FlatFLRWMixin(*args, **kw)

  Bases: `FlatCosmologyMixin`

  Mixin class for flat FLRW cosmologies. Do NOT instantiate directly. Must precede the base class in the multiple-inheritance so that this mixin’s `__init__` proceeds the base class’. Note that all instances of `FlatFLRWMixin` are flat, but not all flat cosmologies are instances of `FlatFLRWMixin`. As example, `LambdaCDM` may be flat (for the a specific set of parameter values), but `FlatLambdaCDM` will be flat.

  Attributes Summary

  `Ode0` | Omega dark energy; dark energy density/critical density at z=0.
  `Otot0` | Omega total; the total density/critical density at z=0.
  `is_flat` | Return `True`, the cosmology is flat.
  `nonflat` | Return the equivalent non-flat-class instance of this cosmology.

  Methods Summary

  `Otot`(z) | The total density parameter at redshift `z`.
  `clone`(*[, meta, to_nonflat]) | Returns a copy of this object with updated parameters, as specified.

  Attributes Documentation

  Ode0

    Omega dark energy; dark energy density/critical density at z=0.

  Otot0

    Omega total; the total density/critical density at z=0.

  is_flat

    Return `True`, the cosmology is flat.

  nonflat

  Methods Documentation

  Otot(z)

    The total density parameter at redshift `z`.

    Parameters:
      z Quantity-like [‘redshift’], numpy:array_like, or `Number`

        Input redshifts.

    Returns:
      Otot `ndarray` or `python:float`

        Returns float if input scalar. Value of 1.

  clone(*, meta: Optional[Mapping] = None, to_nonflat: bool = None, **kwargs: Any)

    Returns a copy of this object with updated parameters, as specified.

    This cannot be used to change the type of the cosmology, except for changing to the non-flat version of this cosmology.

    Parameters:
      meta python:mapping or `python:None` (optional, keyword-only)

        Metadata that will update the current metadata.

      to_nonflat bool or `python:None`, optional keyword-only

        Whether to change to the non-flat version of this cosmology.

      **kwargs

        Cosmology parameter (and name) modifications. If any parameter is changed and a new name is not given, the name will be set to “[old name] (modified)”.

    Returns:
      newcosmo `Cosmology` subclass instance

        A new instance of this class with updated parameters as specified. If no arguments are given, then a reference to this object is returned instead of copy.

    Examples

    To make a copy of the `Planck13` cosmology with a different matter density (`Om0`), and a new name:

        >>> from astropy.cosmology import Planck13
        >>> Planck13.clone(name="Modified Planck 2013", Om0=0.35)
        FlatLambdaCDM(name="Modified Planck 2013", H0=67.77 km / (Mpc s),
          Om0=0.35, ...

    If no name is specified, the new name will note the modification.

        >>> Planck13.clone(Om0=0.35).name
        'Planck13 (modified)'

    The keyword ‘to_nonflat’ can be used to clone on the non-flat equivalent cosmology.

        >>> Planck13.clone(to_nonflat=True)
        LambdaCDM(name="Planck13", ...

        >>> Planck13.clone(H0=70, to_nonflat=True)
        LambdaCDM(name="Planck13 (modified)", H0=70.0 km / (Mpc s), ...

    With ‘to_nonflat’ `True`, `Ode0` can be modified.

        >>> Planck13.clone(to_nonflat=True, Ode0=1)
        LambdaCDM(name="Planck13 (modified)", H0=67.77 km / (Mpc s),
                  Om0=0.30712, Ode0=1.0, ...