# tensorplay.functional.bartlett_window

Source: https://www.tensorplay.cn/docs/generated/tensorplay.functional.bartlett_window.html

```python
tensorplay.functional.bartlett_window(window_length, periodic=True, *, dtype=None, layout=tensorplay.strided, device=None, requires_grad=False) → Tensor
```

Bartlett window function.

$$\begin{split}w[n] = 1 - \left| \frac{2n}{N-1} - 1 \right| = \begin{cases}
    \frac{2n}{N - 1} & \text{if } 0 \leq n \leq \frac{N - 1}{2} \\
    2 - \frac{2n}{N - 1} & \text{if } \frac{N - 1}{2} < n < N \\
\end{cases},\end{split}$$

where $N$ is the full window size.

The input window_length is a positive integer controlling the
returned window size. periodic flag determines whether the returned
window trims off the last duplicate value from the symmetric window and is
ready to be used as a periodic window with functions like
tensorplay.stft(). Therefore, if periodic is true, the $N$ in
above formula is in fact $\text{window\_length} + 1$. Also, we always have
tensorplay.bartlett_window(L, periodic=True) equal to
tensorplay.bartlett_window(L + 1, periodic=False)[:-1]).

> **Note**
>
> If window_length $=1$, the returned window contains a single value 1.

Parameters:

- window_length ([int](https://docs.python.org/3/builtins/functions.html#int)) – the size of returned window

- periodic ([bool](https://docs.python.org/3/builtins/functions.html#bool), optional) – If True, returns a window to be used as periodic function. If False, return a symmetric window.

Keyword Arguments:

- dtype ([tensorplay.dtype](/docs/generated/tensorplay.DType.html#tensorplay.DType), optional) – the desired data type of returned tensor. Default: if None, uses a global default (see [tensorplay.set_default_dtype()](/docs/generated/tensorplay.set_default_dtype.html#tensorplay.set_default_dtype)). Only floating point types are supported.

- layout (tensorplay.layout, optional) – the desired layout of returned window tensor. Only tensorplay.strided (dense layout) is supported.

- device ([tensorplay.device](/docs/generated/tensorplay.Device.html#tensorplay.Device), optional) – the desired device of returned tensor. Default: if None, uses the current device for the default tensor type (see [tensorplay.set_default_device()](/docs/generated/tensorplay.set_default_device.html#tensorplay.set_default_device)). device will be the CPU for CPU tensor types and the current CUDA device for CUDA tensor types.

- requires_grad ([bool](https://docs.python.org/3/builtins/functions.html#bool), optional) – If autograd should record operations on the returned tensor. Default: False.

Returns:

A 1-D tensor of size $(\text{window\_length},)$ containing the window

Return type:

[Tensor](/docs/generated/tensorplay.Tensor.html#tensorplay.Tensor)