/** The following calculates a human body surface area given height and weight (actually mass.) This is based upon an expression for average human surface *area* in the excellent book _Bicycling Science_ by David Gordon Wilson. The expression is attributed to Gehan and George (1970) Gehan E.A., George S.L. Estimation of human body surface area from height and weight. Cancer Chemother Rep 1970;54:225-35. The function can be used as: area[6 feet + 1 inch, 185 lb] -> ft^2 22.426024620760203034 */ area[height, weight] := 0.164 m^2 (height/m)^0.422 (weight/kg)^0.515