REAL FUNCTION ATAN3(A1, A2)
C
C  WORKAROUND FOR ATAN2 BOTH ARGUMENTS = 0
C
      IF (.NOT.(A1 .EQ. 0.0 .AND. A2 .EQ. 0.0)) GOTO 2000
        ATAN3 = 0.0
        GOTO 2010
2000   CONTINUE
        ATAN3 = ATAN2(A1, A2)
2010  CONTINUE
      RETURN
      END