scipy.fft.idst#
- scipy.fft.idst(x, type=2, n=None, axis=-1, norm=None, overwrite_x=False, workers=None, orthogonalize=None)[source]#
Return the Inverse Discrete Sine Transform of an arbitrary type sequence.
- Parameters:
- xarray_like
The input array.
- type{1, 2, 3, 4}, optional
Type of the DST (see Notes). Default type is 2.
- nint, optional
Length of the transform. If
n < x.shape[axis]
, x is truncated. Ifn > x.shape[axis]
, x is zero-padded. The default results inn = x.shape[axis]
.- axisint, optional
Axis along which the idst is computed; the default is over the last axis (i.e.,
axis=-1
).- norm{“backward”, “ortho”, “forward”}, optional
Normalization mode (see Notes). Default is “backward”.
- overwrite_xbool, optional
If True, the contents of x can be destroyed; the default is False.
- workersint, optional
Maximum number of workers to use for parallel computation. If negative, the value wraps around from
os.cpu_count()
. Seefft
for more details.- orthogonalizebool, optional
Whether to use the orthogonalized IDST variant (see Notes). Defaults to
True
whennorm="ortho"
andFalse
otherwise.New in version 1.8.0.
- Returns:
- idstndarray 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 thedst
andidst
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 (seedst
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.