PROGRAM BT2_5
	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)=BMMGOC(X,N,K)
		T(K)=BMMTAM(X,N,K)
	ENDDO

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

	END

	FUNCTION BMMGOC(X,N,K)
! HAM NAY TINH MOMEN GOC BANG PHUONG PHAP PHAN NHOM
! INPUT: + X MANG SO LIEU BAN DAU DO DAI N
!        + N DUNG LUONG MAU
!        + K BAC MOMEN
! OUTPUT: MOMEN GOC BAC K
! FUNCTION/SUBROUTINE DUOC GOI TOI: 
!         FREQ(X,N,XC,FR,F,NFR,M,XMIN,STEP,INTERVAL)
!
	INTEGER N,M,I
	REAL X(N), XC(N), NFR(N), FR(N),F(N)
	REAL XMIN,STEP, TMP
	CALL FREQ(X,N,XC,FR,F,NFR,M,XMIN,STEP,0)
	TMP=0.0
	DO I=1,M
	   TMP=TMP+NFR(I)*XC(I)**K
	ENDDO
	BMMGOC=TMP/REAL(N)
	RETURN
	END

	FUNCTION BMMTAM(X,N,K)
! HAM NAY TINH MOMEN TRUNG TAM BANG PHUONG PHAP PHAN NHOM
! INPUT: + + X MANG SO LIEU BAN DAU DO DAI N
!        + N DUNG LUONG MAU
!        + K BAC MOMEN
! OUTPUT: MOMEN TRUNG TAM BAC K
! FUNCTION/SUBROUTINE DUOC GOI TOI: 
!         FREQ(X,N,XC,FR,F,NFR,M,XMIN,STEP,INTERVAL)
!         
	REAL X(N), XC(N), NFR(N), FR(N),F(N)
	INTEGER N,M,I
	REAL XMIN,STEP, TMP,TBC
	CALL FREQ(X,N,XC,FR,F,NFR,M,XMIN,STEP,0)
	TBC=0.0
	DO I=1,M
	   TBC=TBC+NFR(I)*XC(I)
	ENDDO
	TBC=TBC/REAL(N)
	DO I=1,M
	   XC(I)=XC(I)-TBC
	   TMP=TMP+NFR(I)*XC(I)**K
	ENDDO
	BMMTAM=TMP/REAL(N)
	RETURN
	END


	SUBROUTINE FREQ(X,N,XC,FR,F,NFR,M,XMIN,STEP,INTERVAL)
C
C  CHUONG TRINH NAY TINH TAN SO (NFR) VA TAN SUAT (FR)
C  CUA MANG X DO DAI N.
C INPUT:  + MANG X CHUA GIA TRI QUAN TRAC CUA BIEN NGAU NHIEN
C         + N LA DUNG LUONG MAU
C         + INTERVAL = 0 NEU LAY SO KHOANG CHIA NGAM DINH
C                    = 1 NEU TU CHON SO KHOANG CHIA 
C OUTPUT: + M LA SO KHOANG CHIA, KHI INTERVAL = 0 THI
C           M = 5*LOG10(N)
C         + XC MANG DO DAI M CHUA TRI SO TRUNG GIAN CUA CAC KHOANG
C         + NFR MANG DO DAI M CHUA TAN SO CAC NHOM
C         + FR MANG DO DAI M CHUA TAN SUAT TICH LUY CAC NHOM (HAM PHAN BO)
C         + F MANG DO DAI M CHUA MAT DO XAC SUAT CAC NHOM
C         + XMIN GIOI HAN DUOI CUA NHOM THU NHAT (<=MIN{X(I)}
C         + STEP BUOC CHIA
C
      REAL X(1),NFR(1),FR(1),XC(1),F(1)
	INTEGER N,INTERVAL,M
	REAL XMIN,XMAX,STEP
	CHARACTER ST*10
C	   
      IF (INTERVAL.EQ.0) THEN
	     M=5*LOG10(REAL(N))
	  ELSE
 10	     WRITE(*,'(A\)') ' CHO SO KHOANG: '
		 READ*, ST
		 READ(ST,*,ERR=100) M
		 GOTO 101
 100     PRINT*,' INVALID NUMERIC INPUT ! AGAIN...'
         GOTO 10
 101     CONTINUE
      ENDIF
C
C  XAC DINH MAX, MIN CUA CHUOI DE TIM GIOI HAN CAC NHOM
      XMIN=X(1)
	  XMAX=X(1)
	  DO I=2,N
	     IF (X(I).LT.XMIN) XMIN=X(I)
		 IF (X(I).GT.XMAX) XMAX=X(I)
	  ENDDO
C
      XMIN=AINT(XMIN)
	  IF (XMIN.LT.0.0) XMIN=XMIN-1.0
	  XMAX=AINT(XMAX)
	  IF (XMAX.GT.0.0) XMAX=AINT(XMAX)+1.0
C
      STEP=(XMAX-XMIN)/REAL(M)
C  NEU MUON CHON BUOC TRON SO THI THEM DONG LENH SAU
C
	STEP=AINT(STEP)+1
C
C  TINH XC
      XC(1)=XMIN+STEP/2.0
	DO J=2,M
	   XC(J)=XC(J-1)+STEP
	ENDDO
C  TINH TAN SO CAC KHOANG VA HAM PHAN BO, HAM MAT DO
      STEP=STEP/2.0
	DO J=1,M
	   NFR(J)=0.0
	   DO I=1,N
	      IF ((X(I).GE.XC(J)-STEP).AND.(X(I).LT.XC(J)+STEP)) THEN
	         NFR(J)=NFR(J) + 1
	      ENDIF
	   ENDDO
	   FR(J)=NFR(J)/REAL(N)
	ENDDO
	STEP=STEP*2.0
	DO J=M,1,-1
	   F(J)=FR(J)/STEP
	   TEMP=0.0
	   DO K=1,J
	      TEMP=TEMP+FR(K)
	   ENDDO
	   FR(J)=TEMP
	ENDDO
	RETURN
	END