PostgreSQL/PostGIS - Close approximation of distance in degrees for a given surface distance in meter at a given location and in a given direction

ST_SurfaceToDegree.sql

/*
 * Distance in degree to the curve of an ellipse defined by the factor of latitudinal distance at a given
 * longitude [x-axis] and 1.0 [y-axis], representing the varying factor by which longitudinal degrees scale
 * to latitudinal degrees in relation to surface distance and varying angular direction of measurement.
 *
 * Returns a very close approximation of distance in degree of a sphere at given @latitude that corresponds to
 * @distance meter surface distance, in the direction of north based @azimuth in degree, from the center of the ellipse.
 * Angularity defaults to 90.0 (eastward) and shortcuts execution - corresponds to the simple factor of
 * reduced surface distance per degree of longitude at increasing latitudes.
 */

CREATE OR REPLACE FUNCTION ST_SurfaceToDegree(
  latitude FLOAT,
  distance FLOAT,
  azimuth  FLOAT DEFAULT 90.0
) RETURNS FLOAT IMMUTABLE STRICT PARALLEL SAFE
  LANGUAGE 'plpgsql' AS
  $BODY$
  BEGIN
    IF azimuth IN (90.0, 180.0) THEN
      RETURN DEGREES(distance / (6371000.0 * COS(RADIANS(latitude))));
    END IF;
	
    RETURN SQRT((distance * COS(RADIANS(azimuth - 90))) ^ 2 + (distance / 111194.926 * SIN(RADIANS(azimuth - 90))) ^ 2);
  END;
  $BODY$
;