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# atoti.array.prefix_sum()

### atoti.array.prefix\_sum(measure, /)

Return a measure equal to the sum of the previous elements in the passed array measure.

### Example

If an array has the following values: `[2.0, 1.0, 0.0, 3.0]`, the returned array will be: `[2.0, 3.0, 3.0, 6.0]`.

* **Parameters:**
  **measure** (*VariableMeasureConvertible*)
* **Return type:**
  *MeasureDefinition*