主题:BISECTION 解題求助??
請問下面題目要如何用下面的程序去算出來呢??
因為我才剛開始學FORTRAN 目前連式子的表達式都寫不太出來
聽說只要改方程式就能算出來了??不過我在DEBUG時都出現錯誤
應該是我的方程式寫錯了吧!麻煩各位高手幫我看一下囉!
我替換掉的方程式:1.7=((0-32.17)/(2*X**2))*(((EXP(X)-EXP(-X))/2)-(SIN(X)))
[img]http://img837.imageshack.us/img837/1448/37097998.jpg[/img]
C***********************************************************************
C *
C BISECTION ALGORITHM 2.1 *
C *
C***********************************************************************
C
C
C TO FIND A SOLUTION TO F(X)=0 GIVEN THE CONTINOUS FUNCTION
C F ON THE INTERVAL <A,B>, WHERE F(A) AND F(B) HAVE
C OPPOSITE SIGNS:
C
C INPUT: ENDPOINTS A,B; TOLERANCE TOL;
C MAXIMUM INTERATIONS N0.
C
C OUTPUT: APPROXIMATE SOLUTION P OR A
C MESSAGE THAT THE ALGORITHM FAILS.
C
CHARACTER NAME1*14,AA*1
INTEGER OUP,FLAG
LOGICAL OK
REAL A,B,FA,FB,X,TOL
INTEGER N0
C DEFINE F
F(X)=(X+4)*X*X-10
OPEN(UNIT=5,FILE='CON',ACCESS='SEQUENTIAL')
OPEN(UNIT=6,FILE='CON',ACCESS='SEQUENTIAL')
WRITE(6,*) 'This is the Bisection Method.'
WRITE(6,*) 'Has the function F been created in the program? '
WRITE(6,*) 'Enter Y or N '
WRITE(6,*) ' '
READ(5,*) AA
IF(( AA .EQ. 'Y' ) .OR. ( AA .EQ. 'y' )) THEN
OK = .FALSE.
10 IF (OK) GOTO 11
WRITE(6,*) 'Input endpoints A < B separated by blank '
WRITE(6,*) ' '
READ(5,*) A, B
IF (A.GT.B) THEN
X = A
A = B
B = X
ENDIF
IF (A.EQ.B) THEN
WRITE(6,*) 'A cannot equal B '
WRITE(6,*) ' '
ELSE
FA = F( A )
FB = F( B )
IF ( FA * FB .GT. 0.0 ) THEN
WRITE(6,*) 'F(A) and F(B) have same sign '
WRITE(6,*) ' '
ELSE
OK = .TRUE.
ENDIF
ENDIF
GOTO 10
11 OK = .FALSE.
12 IF (OK) GOTO 13
WRITE(6,*) 'Input tolerance '
WRITE(6,*) ' '
READ(5,*) TOL
IF (TOL.LE.0.0) THEN
WRITE(6,*) 'Tolerance must be positive '
WRITE(6,*) ' '
ELSE
OK = .TRUE.
ENDIF
GOTO 12
13 OK = .FALSE.
14 IF (OK) GOTO 15
WRITE(6,*) 'Input maximum number of iterations '
WRITE(6,*) '- no decimal point '
WRITE(6,*) ' '
READ(5,*) N0
IF ( N0 .LE. 0 ) THEN
WRITE(6,*) 'Must be positive integer '
WRITE(6,*) ' '
ELSE
OK = .TRUE.
ENDIF
GOTO 14
15 CONTINUE
ELSE
WRITE(6,*) 'The program will end so that the function F '
WRITE(6,*) 'can be created '
OK = .FALSE.
ENDIF
IF (.NOT.OK) GOTO 40
WRITE(6,*) 'Select output destination: '
WRITE(6,*) '1. Screen '
WRITE(6,*) '2. Text file '
WRITE(6,*) 'Enter 1 or 2 '
WRITE(6,*) ' '
READ(5,*) FLAG
IF ( FLAG .EQ. 2 ) THEN
WRITE(6,*) 'Input the file name in the form - '
WRITE(6,*) 'drive:name.ext'
WRITE(6,*) 'with the name contained within quotes'
WRITE(6,*) 'as example: ''A:OUTPUT.DTA'' '
WRITE(6,*) ' '
READ(5,*) NAME1
OUP = 3
OPEN(UNIT=OUP,FILE=NAME1,STATUS='NEW')
ELSE
OUP = 6
ENDIF
WRITE(6,*) 'Select amount of output '
WRITE(6,*) '1. Answer only '
WRITE(6,*) '2. All intermediate approximations '
WRITE(6,*) 'Enter 1 or 2 '
WRITE(6,*) ' '
READ(5,*) FLAG
WRITE(OUP,*) 'BISECTION METHOD'
IF (FLAG.EQ.2) THEN
WRITE(OUP,004)
004 FORMAT(3X,'I',15X,'P',12X,'F(P)')
ENDIF
C STEP 1
I=1
C STEP 2
016 IF (I.GT.N0) GOTO 020
C STEP 3
C COMPUTE P(I)
P=A+(B-A)/2
FP=F(P)
IF (FLAG.EQ.2) THEN
WRITE(OUP,005) I,P,FP
005 FORMAT(1X,I3,2X,E15.8,2X,E15.8)
ENDIF
C STEP 4
IF( ABS(FP).LE.1.0E-20 .OR. (B-A)/2 .LT. TOL) THEN
C PROCEDURE COMPLETED SUCCESSFULLY
WRITE(OUP,002) P, I, TOL
GOTO 040
ENDIF
C STEP 5
I=I+1
C STEP 6
C COMPUTE A(I) AND B(I)
IF( FA*FP .GT. 0) THEN
A=P
FA=FP
ELSE
B=P
FB=FP
ENDIF
GOTO 016
020 CONTINUE
C STEP 7
C PROCEDURE COMPLETED UNSUCCESSFULLY
IF(OUP.NE.6) WRITE(6,3) N0,P,TOL
WRITE(OUP,3) N0,P,TOL
040 CLOSE(UNIT=5)
CLOSE(UNIT=OUP)
IF (OUP.NE.6) CLOSE(UNIT=6)
STOP
002 FORMAT(1X,'THE APPROXIMATE SOLUTION IS',/,1X
*,E15.8,1X,'AFTER',1X,I2,1X,'ITERATIONS, WITH TOLERANCE'
* ,1X,E15.8)
003 FORMAT(1X,'ITERATION NUMBER',1X,I3,1X,'GAVE APPROXIMATION',
*/,E15.8,1X,'NOT WITHIN TOLERANCE',1X,E15.8)
END
因為我才剛開始學FORTRAN 目前連式子的表達式都寫不太出來
聽說只要改方程式就能算出來了??不過我在DEBUG時都出現錯誤
應該是我的方程式寫錯了吧!麻煩各位高手幫我看一下囉!
我替換掉的方程式:1.7=((0-32.17)/(2*X**2))*(((EXP(X)-EXP(-X))/2)-(SIN(X)))
[img]http://img837.imageshack.us/img837/1448/37097998.jpg[/img]
C***********************************************************************
C *
C BISECTION ALGORITHM 2.1 *
C *
C***********************************************************************
C
C
C TO FIND A SOLUTION TO F(X)=0 GIVEN THE CONTINOUS FUNCTION
C F ON THE INTERVAL <A,B>, WHERE F(A) AND F(B) HAVE
C OPPOSITE SIGNS:
C
C INPUT: ENDPOINTS A,B; TOLERANCE TOL;
C MAXIMUM INTERATIONS N0.
C
C OUTPUT: APPROXIMATE SOLUTION P OR A
C MESSAGE THAT THE ALGORITHM FAILS.
C
CHARACTER NAME1*14,AA*1
INTEGER OUP,FLAG
LOGICAL OK
REAL A,B,FA,FB,X,TOL
INTEGER N0
C DEFINE F
F(X)=(X+4)*X*X-10
OPEN(UNIT=5,FILE='CON',ACCESS='SEQUENTIAL')
OPEN(UNIT=6,FILE='CON',ACCESS='SEQUENTIAL')
WRITE(6,*) 'This is the Bisection Method.'
WRITE(6,*) 'Has the function F been created in the program? '
WRITE(6,*) 'Enter Y or N '
WRITE(6,*) ' '
READ(5,*) AA
IF(( AA .EQ. 'Y' ) .OR. ( AA .EQ. 'y' )) THEN
OK = .FALSE.
10 IF (OK) GOTO 11
WRITE(6,*) 'Input endpoints A < B separated by blank '
WRITE(6,*) ' '
READ(5,*) A, B
IF (A.GT.B) THEN
X = A
A = B
B = X
ENDIF
IF (A.EQ.B) THEN
WRITE(6,*) 'A cannot equal B '
WRITE(6,*) ' '
ELSE
FA = F( A )
FB = F( B )
IF ( FA * FB .GT. 0.0 ) THEN
WRITE(6,*) 'F(A) and F(B) have same sign '
WRITE(6,*) ' '
ELSE
OK = .TRUE.
ENDIF
ENDIF
GOTO 10
11 OK = .FALSE.
12 IF (OK) GOTO 13
WRITE(6,*) 'Input tolerance '
WRITE(6,*) ' '
READ(5,*) TOL
IF (TOL.LE.0.0) THEN
WRITE(6,*) 'Tolerance must be positive '
WRITE(6,*) ' '
ELSE
OK = .TRUE.
ENDIF
GOTO 12
13 OK = .FALSE.
14 IF (OK) GOTO 15
WRITE(6,*) 'Input maximum number of iterations '
WRITE(6,*) '- no decimal point '
WRITE(6,*) ' '
READ(5,*) N0
IF ( N0 .LE. 0 ) THEN
WRITE(6,*) 'Must be positive integer '
WRITE(6,*) ' '
ELSE
OK = .TRUE.
ENDIF
GOTO 14
15 CONTINUE
ELSE
WRITE(6,*) 'The program will end so that the function F '
WRITE(6,*) 'can be created '
OK = .FALSE.
ENDIF
IF (.NOT.OK) GOTO 40
WRITE(6,*) 'Select output destination: '
WRITE(6,*) '1. Screen '
WRITE(6,*) '2. Text file '
WRITE(6,*) 'Enter 1 or 2 '
WRITE(6,*) ' '
READ(5,*) FLAG
IF ( FLAG .EQ. 2 ) THEN
WRITE(6,*) 'Input the file name in the form - '
WRITE(6,*) 'drive:name.ext'
WRITE(6,*) 'with the name contained within quotes'
WRITE(6,*) 'as example: ''A:OUTPUT.DTA'' '
WRITE(6,*) ' '
READ(5,*) NAME1
OUP = 3
OPEN(UNIT=OUP,FILE=NAME1,STATUS='NEW')
ELSE
OUP = 6
ENDIF
WRITE(6,*) 'Select amount of output '
WRITE(6,*) '1. Answer only '
WRITE(6,*) '2. All intermediate approximations '
WRITE(6,*) 'Enter 1 or 2 '
WRITE(6,*) ' '
READ(5,*) FLAG
WRITE(OUP,*) 'BISECTION METHOD'
IF (FLAG.EQ.2) THEN
WRITE(OUP,004)
004 FORMAT(3X,'I',15X,'P',12X,'F(P)')
ENDIF
C STEP 1
I=1
C STEP 2
016 IF (I.GT.N0) GOTO 020
C STEP 3
C COMPUTE P(I)
P=A+(B-A)/2
FP=F(P)
IF (FLAG.EQ.2) THEN
WRITE(OUP,005) I,P,FP
005 FORMAT(1X,I3,2X,E15.8,2X,E15.8)
ENDIF
C STEP 4
IF( ABS(FP).LE.1.0E-20 .OR. (B-A)/2 .LT. TOL) THEN
C PROCEDURE COMPLETED SUCCESSFULLY
WRITE(OUP,002) P, I, TOL
GOTO 040
ENDIF
C STEP 5
I=I+1
C STEP 6
C COMPUTE A(I) AND B(I)
IF( FA*FP .GT. 0) THEN
A=P
FA=FP
ELSE
B=P
FB=FP
ENDIF
GOTO 016
020 CONTINUE
C STEP 7
C PROCEDURE COMPLETED UNSUCCESSFULLY
IF(OUP.NE.6) WRITE(6,3) N0,P,TOL
WRITE(OUP,3) N0,P,TOL
040 CLOSE(UNIT=5)
CLOSE(UNIT=OUP)
IF (OUP.NE.6) CLOSE(UNIT=6)
STOP
002 FORMAT(1X,'THE APPROXIMATE SOLUTION IS',/,1X
*,E15.8,1X,'AFTER',1X,I2,1X,'ITERATIONS, WITH TOLERANCE'
* ,1X,E15.8)
003 FORMAT(1X,'ITERATION NUMBER',1X,I3,1X,'GAVE APPROXIMATION',
*/,E15.8,1X,'NOT WITHIN TOLERANCE',1X,E15.8)
END