# Example of a mathematical expression

The example below shows a mathematical expression for a 3x3 weighted convolution where there is a weighting for each value in the sliding window.

The **Set Mean** element contains the weighted data point values for a sliding 3x3 window of samples (using a **Grid** element) in the input operand 1 (V1). The result of the **Set Mean** is multiplied by the number of data points in the sliding window and then divided by the sum of the weightings for the data points.

This is the equivalent of the Echoview 3x3 convolution kernel:

3 | 2 | 3 |

2 | 1 | 1 |

3 | 2 | 1 |

**Note:** The formula operator does not account for data type when it evaluates operations on data values. As a consequence, you need to be aware of your data types and design your formulae with respect to linear domain and dB domain calculations accordingly. Refer to Input operands, pings, samples and data values for more information.

#### See also

About the Formula operator

Creating a formula

Formula operator