# tensorplay.functional.cumsum

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

```python
tensorplay.functional.cumsum(input, dim, *, dtype=None, out=None) → Tensor
```

Returns the cumulative sum of elements of input in the dimension
dim.

For example, if input is a vector of size N, the result will also be
a vector of size N, with elements.

$$y_i = x_1 + x_2 + x_3 + \dots + x_i$$

Parameters:

- input ([Tensor](/docs/generated/tensorplay.Tensor.html#tensorplay.Tensor)) – the input tensor.

- dim ([int](https://docs.python.org/3/builtins/functions.html#int)) – the dimension to do the operation over

Keyword Arguments:

- dtype ([tensorplay.dtype](/docs/generated/tensorplay.DType.html#tensorplay.DType), optional) – the desired data type of returned tensor. If specified, the input tensor is casted to dtype before the operation is performed. This is useful for preventing data type overflows. Default: None.

- out ([Tensor](/docs/generated/tensorplay.Tensor.html#tensorplay.Tensor), optional) – the output tensor.

Example:

```
>>> a = tensorplay.randint(1, 20, (10,))
>>> a
tensor([13,  7,  3, 10, 13,  3, 15, 10,  9, 10])
>>> tensorplay.cumsum(a, dim=0)
tensor([13, 20, 23, 33, 46, 49, 64, 74, 83, 93])
```