dct#

ivy.dct(x, /, *, type=2, n=None, axis=-1, norm=None, out=None)[source]#

Compute the 1D Discrete Cosine Tranformation of a given signal.

Parameters:

x (Union[Array, NativeArray]) – The input signal.
type (Literal[1, 2, 3, 4]) – The type of the dct. Must be 1, 2, 3 or 4. (default: 2)
n (Optional[int]) – The lenght of the transform. If n is less than the input signal lenght, (default: None) then x is truncated, if n is larger then x is zero-padded.
axis (int) – The axis to compute the DCT along. (default: -1)
norm (Optional[Literal[‘ortho’]]) – The type of normalization to be applied. Must be either None or “ortho”. (default: None)
out (Optional[Union[Array, NativeArray]]) – optional output array, for writing the result to. (default: None)

Return type:

Union[Array, NativeArray]

Returns:

ret – Array containing the transformed input.
Both the description and the type hints above assumes an array input for simplicity,
but this function is nestable, and therefore also accepts ivy.Container
instances in place of any of the arguments.

Examples

With ivy.Array input:

>>> x = ivy.array([8, 16, 24, 32, 40, 48, 56, 64])
>>> ivy.dct(x, type=2, n=None, norm='ortho')
ivy.array([102., -51.5, 0., -5.39, 0., -1.61, 0., -0.406])

>>> x = ivy.array([[[8, 16, 24, 32], [40, 48, 56, 64]],
...                [[1,  2,  3,  4], [ 5,  6,  7,  8]]])
>>> ivy.dct(x, type=1, n=None, axis=0, norm=None)
ivy.array([[[ 9., 18., 27., 36.],
            [45., 54., 63., 72.]],
           [[ 7., 14., 21., 28.],
            [35., 42., 49., 56.]]])

>>> x = ivy.array([[ 8.1, 16.2, 24.3, 32.4],
...                [40.5, 48.6, 56.7, 64.8]])
>>> y = ivy.zeros((2, 4), dtype=ivy.float32)
>>> ivy.dct(x, type=1, n=None, norm=None, out=y)
>>> print(y)
ivy.array([[ 1.22e+02, -3.24e+01,  1.91e-06, -8.10e+00],
           [ 3.16e+02, -3.24e+01,  3.81e-06, -8.10e+00]])

>>> x = ivy.array([8., 16., 24., 32., 40., 48., 56., 64.])
>>> ivy.dct(x, type=4, n=None, norm=None, out=x)
>>> print(x)
ivy.array([ 279. , -280. ,  128. , -115. ,   83.7,  -79.5,   69.8,  -68.7])

With one ivy.Container input:

>>> x = ivy.Container(a=ivy.array([8, 16, 24, 32, 40, 48, 56, 64]),
...                   b=ivy.array([1,  2,  3,  4,  5,  6,  7,  8]))
>>> ivy.dct(x, type=3, n=None, norm='ortho')
{
    a: ivy.array([79.5, -70.4, 30., -23.6, 13.9, -10.1, 5.2, -1.95]),
    b: ivy.array([9.94, -8.8, 3.75, -2.95, 1.74, -1.26, 0.65, -0.244])
}

With multiple ivy.Container inputs:

>>> x = ivy.Container(a=ivy.array([8, 16, 24, 32, 40, 48, 56, 64]),
...                   b=ivy.array([1,  2,  3,  4,  5,  6,  7,  8]))
>>> container_n = ivy.Container(a=9, b=4)
>>> container_type = ivy.Container(a=2, b=1)
>>> container_norm = ivy.Container(a="ortho", b=None)
>>> ivy.dct(x, type=container_type, n=container_n, norm=container_norm)
{
    a: ivy.array([96., -28.2, -31.9, 22.9, -26., 19.8, -17., 10.9,
                -5.89]),
    b: ivy.array([15., -4., 0., -1.])
}

Array.dct(self, /, *, type=2, n=None, axis=-1, norm=None, out=None)#

ivy.Array instance method variant of ivy.dct. This method simply wraps the function, and so the docstring for ivy.dct also applies to this method with minimal changes.

Parameters:

self (Array) – The input signal.
type (Literal[1, 2, 3, 4]) – The type of the dct. Must be 1, 2, 3 or 4. (default: 2)
n (Optional[int]) – The lenght of the transform. If n is less than the input signal lenght, (default: None) then x is truncated, if n is larger than x is zero-padded.
norm (Optional[Literal[‘ortho’]]) – The type of normalization to be applied. Must be either None or “ortho”. (default: None)
out (Optional[Array]) – optional output array, for writing the result to. (default: None)

Return type:

Array

Returns:

ret – Array containing the transformed input.

Examples

>>> x = ivy.array([8., 16., 24., 32., 40., 48., 56., 64.])
>>> x.dct(type=2, norm="ortho")
ivy.array([ 102.,  -51.5,   0.,  -5.39,   0.,  -1.61,   0., -0.406])

Container.dct(self, /, *, type=2, n=None, axis=-1, norm=None, out=None)#

ivy.Container instance method variant of ivy.dct. This method simply wraps the function, and so the docstring for ivy.dct also applies to this method with minimal changes.

Parameters:

self (Container) – Container with the input signals.
type (Literal[1, 2, 3, 4]) – The type of the dct. Must be 1, 2, 3 or 4. (default: 2)
n (Optional[int]) – The lenght of the transform. If n is less than the input signal lenght, (default: None) then x is truncated, if n is larger then x is zero-padded.
norm (Optional[Literal[‘ortho’]]) – The type of normalization to be applied. Must be either None or “ortho”. (default: None)
out (Optional[Container]) – optional output container, for writing the result to. (default: None)

Return type:

Container

Returns:

ret – The transformed input.

Examples

>>> x = ivy.Container(a=ivy.array([8, 16, 24, 32, 40, 48, 56, 64]),
...                   b=ivy.array([1,  2,  3,  4,  5,  6,  7,  8]))
>>> x.dct(type=2, norm='ortho')
{
    a: ivy.array([102., -51.5, 0., -5.39, 0., -1.61, 0.,
                -0.406]),
    b: ivy.array([12.7, -6.44, 0., -0.673, 0., -0.201, 0.,
                -0.0507])
}