2001년 수치해석 포트란 프로그램 레포트

[Cool]

implicit double precision (a-h, o-z)
open(3,file='hw.txt')

write(6,*) '초기값 x1='
read(5,*) x1
write(6,*) '초기값 x2='
read(5,*) x2
write(6,*) '수렴판정 조건 e='
read(5,*) e

n=0
write(3,*) ' n x(n) f(x) x(n+1)-x(n) '
write(3,*) '===================================================='
10 x=(x1*f(x2)-x2*f(x1))/(f(x2)-f(x1))
n=n+1
if(f(x2)*f(x).lt.0) then
write(3,30) n,x,f(x),abs(x1-x)
if(abs(x1-x).le.e) then
goto 20
end if
x1=x
else
write(3,30) n,x,f(x),abs(x2-x)
if(abs(x2-x).le.e) then
goto 20
end if
x2=x
end if
goto 10

20 write(3,*) '===================================================='
30 format(3x,i2,3f12.7)
write(3,40) '답 x=',x
40 format(a12,f10.6)
stop
end

double precision function f(x)

implicit double precision (a-h, o-z)
f=x*x*x-1
return
end



*출력값

n x(n) f(x) x(n+1)-x(n)
====================================================
1 0.1600000 -0.9959040 0.1600000
2 0.3091857 -0.9704431 0.1491857
3 0.4455115 -0.9115747 0.1363258
4 0.5660541 -0.8186265 0.1205426
5 0.6685675 -0.7011620 0.1025134
6 0.7523544 -0.5741395 0.0837868
7 0.8183708 -0.4519119 0.0660164
8 0.8687756 -0.3442734 0.0504048
9 0.9062916 -0.2556044 0.0375160
10 0.9336667 -0.1860914 0.0273752
11 0.9533466 -0.1335320 0.0196799
12 0.9673404 -0.0948136 0.0139938
13 0.9772126 -0.0668162 0.0098722
14 0.9841380 -0.0468351 0.0069254
15 0.9889769 -0.0327060 0.0048389
16 0.9923485 -0.0227793 0.0033716
17 0.9946931 -0.0158363 0.0023446
====================================================
답 x= 0.994693