ðə kˈɔst fˈʌŋkʃən ɪz ˈɔfən dᵻfˈaɪnd æz ɐ sˈʌm ʌvðə dˌiːvɪˈeɪʃənz ʌv kˈiː mˈɛʒɚmənts, lˈaɪk ˈæltɪtˌuːd ɔːɹ pɹˈɑːsɛs tˈɛmpɹɪtʃɚ, fɹʌm ðɛɹ dɪzˈaɪɚd vˈæljuːz.
The cost function is often defined as a sum of the deviations of key measurements, like altitude or process temperature, from their desired values.