---
title: "Define input parameters"
canonical: "https://help.vicon.com/space/ProCalc16/12648917/Define%20input%20parameters"
format: markdown
---
The ProCalc tab for defining input parameters looks like this:

![image](media://60a4ba6a-e605-4113-80af-2d70c0809c49)

**To define input parameters:**

1. Either select an existing parameter to edit, or create a new one by clicking the **Add** button just below the list.
2. Enter a suitable name for the parameter.
3. Select the appropriate type for the parameter:
  - **Subject parameter**. Read from the Vicon Nexus subject parameters associated with the trial, if available, eg: Subject Height.
  - **Constant Parameter**. A constant value, optionally with a unit, eg: PI = 3.14156 (unitless) or ForcePlateLength = 500mm.
  - **Constant Vector. **The 3D equivalent of the constant parameter, eg: ForcePlateOffset = { 300, 200, 0 } mm.
  - **Constant Euler Angle.** The 3D angle equivalent, eg: OffsetAngle= < 15, 30, 0 > deg.
  - **Calculated Parameter.** Used when you need to feed an output parameter from a previously processed trial (typically a static or calibration trial) as an input parameter, eg: WandOffset = 14mm.
4. Enter the relevant value, and select the **Quantity** and **Unit**.
5. If you’ve defined subject measurements for the trial in Nexus, ProCalc automatically recognizes these. If you are defining a Subject Measurement as an input parameter to ProCalc, you will see the Nexus-defined subject measurements in the drop-down list below the parameter name. To automatically complete the parameter name field correctly, select the required subject parameter and then click **Use**.
6. Save the scheme by clicking the **Save** button at the top.