Need help understanding error PLEASE

    r

Answer 1

[Ameer Hamza]

You haven't attached the function fwithforcing(), so I cannot run your code, but I guess that sometimes the value of x(n) becomes negative, which causes an issue with axis() function. The limits in axis() should be in ascending order. Try to change it like this.

axis([sort([0 x(n)]) -Fmax Fmax]); 

Note that you will need to change both calls to axis().

[Triggs]

Sorry about that the function fwithforcing is now attached, if you would like to run the code please,

[Ameer Hamza]

Have you tried the code in my answer?

[Ameer Hamza]

After running your code, I found that the error is caused by Fmax. For some reason, the value of Fmax becomes NaN. You need to check the logic of your code to find out what makes Fmax=NaN.

[Triggs]

I've found the problem on line 116 there is a ^4, when that is removed the entire code works but when its there thats when the errors occur but that term needs to be there. is there any way i can fix that?

    b(i)=b(i)+q(i+1)*dt/dx*U(i+1)^4;

[Ameer Hamza]

I do not clearly understand about your program logic. You need to analyze this according to the equations you have.