urns
    -------
    idst : ndarray of real
        The transformed input array.

    See Also
    --------
    dst : Forward DST

    Notes
    -----
    .. warning:: For ``type in {2, 3}``, ``norm="ortho"`` breaks the direct
                 correspondence with the inverse direct Fourier transform.

    For ``norm="ortho"`` both the `dst` and `idst` are scaled by the same
    overall factor in both directions. By default, the transform is also
    orthogonalized which for types 2 and 3 means the transform definition is
    modified to give orthogonality of the DST matrix (see `dst` for the full
    definitions).

    'The' IDST is the IDST-II, which is the same as the normalized DST-III.

    The IDST is equivalent to a normal DST except for the normalization and
    type. DST type 1 and 4 are their own inverse and DSTs 2 and 3 are each
    other's inverses.

    r