Returns an array of cells for the sum of two time series.

## Syntax

X is the first univariate time series data (a one dimensional array of cells (e.g. rows or columns)).

Y is the second univariate time series data. If a single value is passed, it will be added to all observations in the first time series.

## Remarks

1. The time series is homogeneous or equally spaced.
2. The two time series have an identical number of observations and time order, or the second series contains a single value.
3. In the case where the two time series are identically sized, the two series are added together point-by-point:
$$\left[z_t\right] = \left[x_t\right] + \left[y_t\right]$$
Where:
• $\left[z_t\right]$ is the sum time series.
• $\left[x_t\right]$ is the first time series.
• $\left[y_t\right]$ is the second time series.
4. In the case where the second time series is passed as a single value ($\alpha$), this constant is added to all points in the first time series:
$$\left[z_t\right] =\left[x_t\right] + \left[\alpha\right]$$
Where:
• $\left[z_t\right]$ is the sum time series.
• $\left[x_t\right]$ is the first time series.
• $\alpha$ is a constant value.
5. The returned array has the same size and time order as the first input time series.