# Arrays

Array channels can come from scope trigger, FFT, CPB, STFT, classification, counting and other new procedures. The formula has operations which work on those array channels.

## Extracting subset of the array

To extract a value from an array, use brackets with index. Let’ s say we want to extract one single value of the FFT:

$$’AI0/AmplFFT’[10]$$

## Operation on arrays

Basically, all operation should work on arrays, but there are some limitations to it. We can, for example, do the following:

$$’AI0/AmplFFT’ - ‘AI1/AmplFFT’$$

It is important to know that the product of the two vectors multiplies elements in the array. The resulting array has the same size as the input array.

$$’AI0/AmplFFT’ *’AI1/AmplFFT’$$

We can also for example mix vector and scalar values:

$$’AI0/AmplFFT’ +2$$

This formula will add a value of two to each array element and will output array with the same size as the input.

IMPORTANT: **Arrays with different sizes can’t be combined into a single formula.**