PROGRAM BT2_4
	PARAMETER (NMAX=100)
	DIMENSION X(NMAX)
	INTEGER NAM(NMAX),N,I,K
	REAL G(4),T(4)
	  
	OPEN(1,FILE='C:\MASTER\G_TR\BAITAP~1\NEW\BANG3.TXT')
	READ(1,*)
	READ(1,*)
	READ(1,*)N
      READ(1,*)((NAM(I),X(I)), I=1,N)

	DO K=1,4
		G(K)=AMMGOC(X,N,K)
		T(K)=AMMTAM(X,N,K)
	ENDDO

	WRITE(*,*)' CAC MOMEN TINH BANG PHUONG PHAP TRUC TIEP'
	WRITE(*,*)' BAC ','          MOMEN GOC ','          MOMEN TAM '
	DO K=1,4
	   WRITE(*,'(I5,2F20.3)') K, G(K), T(K)
	ENDDO
	
	END


	  FUNCTION AMMGOC(X,N,K)
!
! HAM NAY TINH MOMEN GOC BAC K CUA CHUOI SO LIEU
! INPUT: + X MANG SO LIEU BAN DAU DO DAI N
!        + N DUNG LUONG MAU
!        + K BAC CUA MOMEN
! OUTPUT: MOMEN GOC BAC K
!
      DIMENSION X(N)
	  INTEGER N,K,I
	  REAL TMP
	  TMP=0.0
	  DO I=1,N
	     TMP=TMP+X(I)**K
	  ENDDO
	  AMMGOC=TMP/REAL(N)
	  RETURN
	  END

	  FUNCTION FAC(N)
! TINH N! (N GIAI THUA)
	  REAL TMP
	  IF (N.LT.0) THEN
	     WRITE(*,*)' INVALID NUMERIC INPUT IN FAC FUNCTION'
		 STOP
	  ELSE IF (N.EQ.0.OR.N.EQ.1) THEN
	     FAC=1.0
		 RETURN
	  ELSE
	     TMP=1.0
		 DO I=2,N
	        TMP=TMP*REAL(I)
		 ENDDO
		 FAC=TMP
		 RETURN
	  ENDIF
	  END

      FUNCTION COMBIN(N,K)
! TINH TO HOP CHAP K CUA N
! FUNCTION/SUBROUTINE DUOC GOI TOI: FAC(N)
	  IF (N.LT.0.OR.K.LT.0.OR.N.LT.K) THEN
	     WRITE(*,*)' INVALID NUMERIC INPUT IN COMBIN FUNCTION'
		 STOP
      ELSE 
         COMBIN=FAC(N)/FAC(K)/FAC(N-K)
	     RETURN
	  ENDIF
	  END

	  FUNCTION AMMTAM(X,N,K)
! HAM NAY TINH MOMEN TRUNG TAM BAC K TU CHUOI SO LIEU X
! INPUT: + X MANG SO LIEU BAN DAU DO DAI N
!        + N DUNG LUONG MAU
!        + K BAC CUA MOMEN
! OUTPUT: MOMEN TRUNG TAM BAC K
! FUNCTION/SUBROUTINE DUOC GOI TOI: AMMGOC(X,N,K), COMBIN(N,K)
	  DIMENSION X(N)
	  INTEGER N,K,I
	  REAL TMP,TB
	  TB=AMMGOC(X,N,1)
	  TMP=0
	  DO I=0,K
	     TMP=TMP+(-1)**I*COMBIN(K,I)*TB**I*AMMGOC(X,N,K-I)
	  ENDDO
	  AMMTAM=TMP
	  RETURN
	  END