UDF to calculate bearing in BigQuery

bearing.sql

#
# https://en.wikipedia.org/wiki/Radian
# https://towardsdatascience.com/calculating-the-bearing-between-two-geospatial-coordinates-66203f57e4b4

CREATE TEMP FUNCTION 
  PI (degree float64) AS (ACOS(-1));

CREATE TEMP FUNCTION
  RADIANS (degree FLOAT64) AS (degree * ACOS(-1) / 180);
CREATE TEMP FUNCTION
  DEGREES (radian FLOAT64) AS (radian * 180 / ACOS(-1));


CREATE TEMP FUNCTION
  BEARING(
    src_lat FLOAT64, src_lng FLOAT64,
    dst_lat FLOAT64, dst_lng FLOAT64
  )
  RETURNS FLOAT64 AS ( 
   DEGREES(
      ATAN2(
         SIN(RADIANS(src_lng-dst_lng))*COS(RADIANS(src_lat)), 
         COS(RADIANS(dst_lat))*SIN(RADIANS(src_lat)) -SIN(RADIANS(dst_lat))*COS(RADIANS(src_lat))* COS(RADIANS(src_lng-dst_lng)) 
      ) 
    )
  );
CREATE TEMP FUNCTION
  BEARING_GEO(p1 GEOGRAPHY, p2 GEOGRAPHY)
  RETURNS FLOAT64 AS ( 
   DEGREES(
      ATAN2(
         SIN(RADIANS(ST_X(p1)-ST_X(p2)))*COS(RADIANS(ST_Y(p1))), 
         COS(RADIANS(ST_Y(p2)))*SIN(RADIANS(ST_Y(p1))) -SIN(RADIANS(ST_Y(p2)))*COS(RADIANS(ST_Y(p1)))* COS(RADIANS(ST_X(p1)-ST_X(p2))) 
      ) 
    )
  );