The Stone–Geary utility function takes the form where is utility, is consumption of good , and and are parameters. For , the Stone–Geary function reduces to the generalised Cobb–Douglas function. The Stone–Geary utility function gives rise to the Linear Expenditure System. In case of the demand function equals where is total expenditure, and is the price of good . The Stone–Geary utility function was first derived by Roy C. Geary, in a comment on earlier work by Lawrence Klein and . Richard Stone was the first to estimate the System.