求找出错误，结果运行正确，但是每当输入大于10 的时，...

freedom · 发表于 2016-4-19 23:56:32

[Fortran] 纯文本查看 复制代码

program mytp21
implicit none 
integer i,j,n
double precision h
double precision,allocatable ::x(:,:),b(:),a(:),c(:),f(:),u(:)
write(6,*)'input un nombre n'
read(5,*)n
allocate(x(n,n),a(n),b(n),c(n),f(n),u(n))
h=1.d0/n
x(1,1)=1.d0/h+1.d0*h/3
f(1)=1.d0
do i=2,n
 f(i)=0
     !write(6,'("(",i3,")=",d15.8)')i,f(i)
     enddo
do i=1,n
    do j=1,n
    if(i==j)then
    x(i+1,j+1)=2.d0*x(1,1)
    elseif(i==j+1)then
    x(i,j)=-1.d0/h+1.d0*h/6.d0
    elseif(j==i+1) then
    x(i,j)=-1.d0/h+1.d0*h/6.d0
    else
    x(i,j)=0
    endif
 enddo
enddo
 do i=1,n
    b(i)=x(i,i)
    !write(6,'("(",i3,")=",d15.8)')i,b(i)
    enddo

    do i=2,n
    a(i)=x(i,i-1)
    ! write(6,'("(",i3,")=",d15.8)')i,a(i)
    enddo
    do i=1,n-1
       c(i)=x(i,i+1)
    ! write(6,'("(",i3,")=",d15.8)')i,c(i)
    end do
    a(1)=0
    c(n)=0
    u(n)=0
    open(30, file='le solution de u(x).txt')
    call tridag(a,b,c,f,u,n)
    do i=1,n
    write(6,'("(",i3,")=",d15.8)')i,u(i)
    write(30,*)'le solution de u(x)',u(i)
    end do
    close(30)
pause


contains

subroutine tridag(a,b,c,f,u,n)
implicit none
integer n
double precision gam(n),a(n),b(n),c(n),u(n),f(n),bet
integer j,n
if (b(1)==0.) pause 'b(1)=0 dans tridag'
 bet=b(1)
u(1)=f(1)/bet
do j=2,n
    gam(j)=c(j-1)/bet
    bet=b(j)-a(j)*gam(j)
    if (bet==0.) pause 'bet=0 dans tridag'
    u(j)=(f(j)-a(j)*u(j-1))/bet
end do
do j=n-1,1,-1
    u(j)=u(j)-gam(j+1)*u(j+1)
end do
 end subroutine tridag
 end program mytp21
!  --------------------------------------------------
!  Silverfrost FTN95 for Microsoft Visual Studio
!  Free Format FTN95 Source File
!  --------------------------------------------------