Computed Attributes

Hello everyone,
I am exploring computed attributes and cannot able to identify where can i see that
in computed attributes docs it says "Computed attributes are applied to all incoming positions of a linked device."
as per my understanding if I assigned a computed attribute to a device then it will come in position websocket message.
if not the case then please tell me how and where can i use this like rest api of something else?

I don't really understand the question. Computed attributes are expression that are executed when you receive some data from a device. There's an API to create and assign them. Hopefully it clarified what they're.

where can i access the result of the execution
for example
i have to calculate voltage from speed by some formula and i want this voltage to be realtime as speed will change and based on that voltage has to be changed

The results are in the position attributes, like all the other data that's coming from devices.

It is not coming in my case
I have created a computed attribute which takes speed and multiple it with number to get voltage( image attached below)
https://imgtr.ee/i/screenshot-2023-06-06-100157-pm.pOIMY
I have attached this to a device and but when i check websocket message of that device, i wasn't able to find one
This is that device websocket position message

{
  "positions": [
    {
      "id": 61867948,
      "attributes": {
        "channel.id": 54861,
        "ignition": true,
        "gnss.realtime.status": true,
        "gsm.cellid": 51602,
        "gsm.lac": 5067,
        "gsm.mcc": 404,
        "gsm.mnc": 49,
        "ident": "358979100209983",
        "peer": "106.211.165.226:19840",
        "sat": 15,
        "protocol.id": 13,
        "protocol.number": 34,
        "report.reason": 0,
        "server.timestamp": 1686069262.951667,
        "distance": 39.12,
        "totalDistance": 11586855,
        "motion": true,
        "hours": 539232000
      },
      "deviceId": 182,
      "serverTime": "2023-06-06T16:34:23.400+00:00",
      "deviceTime": "2023-06-06T16:34:22.000+00:00",
      "fixTime": "2023-06-06T16:34:22.000+00:00",
      "outdated": false,
      "valid": true,
      "latitude": 17.46969,
      "longitude": 78.363884,
      "altitude": 0,
      "speed": 12.958968,
      "course": 233,
      "address": null,
      "accuracy": 0,
      "network": null
    }
  ]
}

I want a key named voltage in this websocket position message

It probably means you haven't linked the attribute to your device.

Just again check it with the new message and it's working
Thank you