PROGRAM POTENCIAL
      IMPLICIT REAL*8 (A-H,O-Z)
C...
      COMMON/POT/POT
      CHARACTER*8 POT
C...
      READ(*,*)POT
      READ(*,*)AL,AM1,AM2,R1,R2
      IF(POT.EQ.'mgz     ')POT='MGZ     '
      IF(POT.EQ.'armonico')POT='ARMONICO'
      IF(POT.EQ.'gravit  ')POT='GRAVIT  '
      G=9.8D0
      DELTA=0.01D0
      NI=1
      NF=(R2-R1)/DELTA+1
      IF(POT.EQ.'MGZ     ')THEN
      AMU=AM1
      AMU1=AM1+AM2
      AM=1.D0
      CT=AM2*G
      ENDIF
      IF(POT.EQ.'ARMONICO')THEN
      AMU=AM1*AM2/(AM1+AM2)
      AMU1=AMU
      AM=AMU/AM2
      CT=0.5D0
      ENDIF
      IF(POT.EQ.'GRAVIT  ')THEN
      AMU=AM1*AM2/(AM1+AM2)
      AMU1=AMU
      AM=AMU/AM2
      CT=-AM1*AM2
      ENDIF
      R=R1
      DO I=NI,NF
      R=R+DELTA
      POTT=AL**2/(2.D0*AMU*R**2)+CT*F(R)
      WRITE(*,1)R,POTT      
      ENDDO
   1  FORMAT(2(2X,F12.5))
      END 
C...
      FUNCTION F(R)
      IMPLICIT REAL*8 (A-H,O-Z)
C...
      COMMON/POT/POT
      CHARACTER*8 POT
C...
      IF(POT.EQ.'MGZ     ')F=R
      IF(POT.EQ.'ARMONICO')F=R**2
      IF(POT.EQ.'GRAVIT  ')F=1.D0/R
      RETURN
      END