jax.numpy.cumsum

jax.numpy.cumsum(a, axis=None, dtype=None, out=None)

Cumulative sum of elements along an axis.

JAX implementation of numpy.cumsum().

Parameters:

• a (ArrayLike) – N-dimensional array to be accumulated.

• axis (int | None) – integer axis along which to accumulate. If None (default), then array will be flattened and accumulated along the flattened axis.

• dtype (DTypeLike | None) – optionally specify the dtype of the output. If not specified, then the output dtype will match the input dtype.

• out (None) – unused by JAX

Returns:

An array containing the accumulated sum along the given axis.

Return type:

Array

See also

• jax.numpy.cumulative_sum(): cumulative sum via the array API standard.

• jax.numpy.add.accumulate(): cumulative sum via ufunc methods.

• jax.numpy.nancumsum(): cumulative sum ignoring NaN values.

• jax.numpy.sum(): sum along axis

Examples

>>> x = jnp.array([[1, 2, 3],
...                [4, 5, 6]])
>>> jnp.cumsum(x)  # flattened cumulative sum
Array([ 1,  3,  6, 10, 15, 21], dtype=int32)
>>> jnp.cumsum(x, axis=1)  # cumulative sum along axis 1
Array([[ 1,  3,  6],
       [ 4,  9, 15]], dtype=int32)