torch.signal.windows.kaiser

torch.signal.windows.kaiser(M, *, beta=12.0, sym=True, dtype=None, layout=torch.strided, device=None, requires_grad=False)

Computes the Kaiser window.

The Kaiser window is defined as follows:

$$w_n = I_0 \left( \beta \sqrt{1 - \left( {\frac{n - N/2}{N/2}} \right) ^2 } \right) / I_0( \beta )$$

where I_0 is the zeroth order modified Bessel function of the first kind (see torch.special.i0()), and N = M - 1 if sym else M.

The window is normalized to 1 (maximum value is 1). However, the 1 doesn’t appear if M is even and sym is True.

Parameters

M (int) – the length of the window. In other words, the number of points of the returned window.

Keyword Arguments

• beta (float, optional) – shape parameter for the window. Must be non-negative. Default: 12.0

• sym (bool, optional) – If False, returns a periodic window suitable for use in spectral analysis. If True, returns a symmetric window suitable for use in filter design. Default: True.

• dtype (torch.dtype, optional) – the desired data type of returned tensor. Default: if None, uses a global default (see torch.set_default_dtype()).

• layout (torch.layout, optional) – the desired layout of returned Tensor. Default: torch.strided.

• device (torch.device, optional) – the desired device of returned tensor. Default: if None, uses the current device for the default tensor type (see torch.set_default_device()). device will be the CPU for CPU tensor types and the current CUDA device for CUDA tensor types.

• requires_grad (bool, optional) – If autograd should record operations on the returned tensor. Default: False.

Return type

Tensor

Examples:

>>> # Generates a symmetric gaussian window with a standard deviation of 1.0.
>>> torch.signal.windows.kaiser(5)
tensor([4.0065e-05, 2.1875e-03, 4.3937e-02, 3.2465e-01, 8.8250e-01, 8.8250e-01, 3.2465e-01, 4.3937e-02, 2.1875e-03, 4.0065e-05])
>>> # Generates a periodic gaussian window and standard deviation equal to 0.9.
>>> torch.signal.windows.kaiser(5, sym=False,std=0.9)
tensor([1.9858e-07, 5.1365e-05, 3.8659e-03, 8.4658e-02, 5.3941e-01, 1.0000e+00, 5.3941e-01, 8.4658e-02, 3.8659e-03, 5.1365e-05])