Creates a function in MariaDB for the computation of the heat index

heatindex-function.sql

CREATE OR REPLACE FUNCTION CalcHeatIndex(IN T FLOAT, IN RH FLOAT) RETURNS FLOAT

BEGIN
  # https://www.wpc.ncep.noaa.gov/html/heatindex_equation.shtml
	DECLARE HI, HI2, HI2a, HI3 float;
	SET T = ((T*9/5)+32 ); # convert C to F
	SET HI = (0.5*(T + 61.0 + ((T-68.0)*1.2) + (RH*0.094)));
	SET HI2 = (-42.379 + 2.04901523*T + 10.14333127*RH - 0.22475541*T*RH - 0.00683783*T*T - 0.05481717*RH*RH + 0.00122874*T*T*RH + 0.00085282*T*RH*RH - 0.00000199*T*T*RH*RH);
	SET HI2a = - ((13-RH)/4)*sqrt((17-abs(T-95))/17);
	SET HI3 = CASE	WHEN (HI < 80) THEN HI 
			WHEN (RH > 85 AND T > 80 AND T < 87) THEN HI2-HI2a
			ELSE HI2 END;
	SET HI3 = (HI3-32)*5/9;
	RETURN HI3;
END