# tensorplay.signal.windows.cosine

Source: https://www.tensorplay.cn/docs/generated/tensorplay.signal.windows.cosine.html

```python
tensorplay.signal.windows.cosine(M: int, *, sym: bool = True, dtype: dtype | None = None, layout: Layout = tensorplay.strided, device: device | None = None, requires_grad: bool = False) → Tensor
```

Computes a window with a simple cosine waveform, also known as the sine
window.

The samples follow

$$w_n = \sin\left(\frac{\pi (n + 0.5)}{M}\right)$$

The 0.5 in the numerator shifts the sample positions by half a step, so the
window starts and ends at non-zero values (for a symmetric window the first
and last samples equal sin(pi / (2M))).

The window is scaled so that its largest value is 1. The value 1 itself does not occur when M is even and sym is True.

Parameters:

M ([int](https://docs.python.org/3/builtins/functions.html#int)) – number of points of the returned window.

Keyword Arguments:

- sym ([bool](https://docs.python.org/3/builtins/functions.html#bool), optional) – if False, returns a periodic window, which is the usual choice for spectral analysis. If True, returns a symmetric window, which is the usual choice for filter design. Default: True.

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

- layout ([tensorplay.Layout](/docs/generated/tensorplay.Layout.html#tensorplay.Layout), optional) – the desired layout of the returned tensor. Default: tensorplay.strided.

- device ([tensorplay.device](/docs/generated/tensorplay.Device.html#tensorplay.Device), optional) – the desired device of the returned tensor. Default: if None, uses the current default tensor device (see [tensorplay.set_default_device()](/docs/generated/tensorplay.set_default_device.html#tensorplay.set_default_device)).

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

Examples:

```
>>> # Symmetric cosine window.
>>> tensorplay.signal.windows.cosine(10)
tensor([0.1564, 0.454, 0.7071, 0.891, 0.9877, 0.9877, 0.891, 0.7071, 0.454, 0.1564])

>>> # Periodic cosine window.
>>> tensorplay.signal.windows.cosine(10, sym=False)
tensor([0.1423, 0.4154, 0.6549, 0.8413, 0.9595, 1., 0.9595, 0.8413, 0.6549, 0.4154])
```