"Nan" Fortran

[mater]

Hi everybody,
while I was working on a finite difference method, I came across with a mistake. I am new in programming. Could you please help me how to get over this problem? These are the codes:

           dimension U(100),UO(100)
                 INTEGER::IMAX=10
                REAL:: DX=0.0182,DT=0.1

    IMAX1=IMAX-1
    do 2 I=1,IMAX
    U(I)=0
2    UO(I)=0
    T=0
    N=0
100    T=T+DT
    N=N+1
    if(T.LT.0.1) GO TO 22
    U(IMAX)=10
    go to 23
22    U(IMAX)=T*100
23    continue
    do 3 I=2,IMAX1
3    U(I)=UO(I)+DT*1./DX**2.*(UO(I+1)+UO(I-1)-2.*UO(I))
    DO 4 I=1,IMAX
4    UO(I)=U(I)
    write(6,5)(UO(I),I=1,IMAX)
5    format(d17.10)
    if(N.LT.150) go to 100
    stop
    end

Thank you very much If someone interested in. Have a nice day

[dargueta]

Where are you getting the NaN error? Do you have a debugger to single-step the code?