CREATE OR REPLACE FUNCTION "public"."pm25_aqi"("pm25_nd" numeric)

  RETURNS "pg_catalog"."int4" AS $BODY$

DECLARE

    RET numeric;

    IAQI_1 numeric;

    IAQI_2 numeric;

    IAQI_3 numeric;

    IAQI_4 numeric;

    IAQI_5 numeric;

    IAQI_6 numeric;

    IAQI_7 numeric;

    IAQI_8 numeric;

    BP_1 numeric;

    BP_2 numeric;

    BP_3 numeric;

    BP_4 numeric;

    BP_5 numeric;

    BP_6 numeric;

    BP_7 numeric;

    BP_8 numeric;

BEGIN

    IAQI_1=0;

    IAQI_2=50;

    IAQI_3=100;

    IAQI_4=150;

    IAQI_5=200;

    IAQI_6=300;

    IAQI_7=400;

    IAQI_8=500;

    BP_1=0;

    BP_2=35;

    BP_3=75;

    BP_4=115;

    BP_5=150;

    BP_6=250;

    BP_7=350;

    BP_8=500;

     IF   PM25_ND<=BP_2

      THEN RET = ((IAQI_2-IAQI_1)/(BP_2-BP_1))*(PM25_ND-BP_1)+IAQI_1;

    ELSIF PM25_ND>BP_2 AND PM25_ND<=BP_3

     THEN  RET = ((IAQI_3-IAQI_2)/(BP_3-BP_2))*(PM25_ND-BP_2)+IAQI_2;

    ELSIF PM25_ND>BP_3 AND PM25_ND<=BP_4

      THEN RET = ((IAQI_4-IAQI_3)/(BP_4-BP_3))*(PM25_ND-BP_3)+IAQI_3;

    ELSIF PM25_ND>BP_4 AND PM25_ND<=BP_5

      THEN RET = ((IAQI_5-IAQI_4)/(BP_5-BP_4))*(PM25_ND-BP_4)+IAQI_4;

    ELSIF PM25_ND>BP_5 AND PM25_ND<=BP_6

     THEN  RET = ((IAQI_6-IAQI_5)/(BP_6-BP_5))*(PM25_ND-BP_5)+IAQI_5;

    ELSIF PM25_ND>BP_6 AND PM25_ND<=BP_7

     THEN  RET = ((IAQI_7-IAQI_6)/(BP_7-BP_6))*(PM25_ND-BP_6)+IAQI_6;

    ELSIF PM25_ND>BP_7

      THEN RET = ((IAQI_8-IAQI_7)/(BP_8-BP_7))*(PM25_ND-BP_7)+IAQI_7;

    END IF;

    IF RET>500 THEN RET=500;  END IF;

    return  ceiling(RET);

END;

$BODY$

  LANGUAGE plpgsql VOLATILE

  COST 100