I only need to interpolate between two signals. The signals are just calculations for flow rate needed based off altitude. So signals are as follows: 1. Flow rate needed at 47500ft and above in altitude 2. Flow rate needed at 23000ft and below in altitude I just need to interpolate between the signals (ex: 35000ft) to get the needed value, where altitude is always known. The flow rate is calculated with variables that can be changing.