index out of bounds because numel(uold)=1 Error

Question

Ishfaq Ahmad Bhat 2016-11-23

0
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https://ww2.mathworks.cn/matlabcentral/answers/313628-index-out-of-bounds-because-numel-uold-1-error

评论： Ishfaq Ahmad Bhat 2016-11-23

Please help in removing the error in matlab code. I tried with changing the variable but that didn't help.

    % Defining constants;
L=10;                 % length of domain in x-direction
tmax=10;              % end time
nx=50;                % number of nodes in x-direction
nt=50;                % number of time steps 
dx=L/(nx-1);           % Length of space interval
dt=tmax/(nt-1);        % Length of time interval
alpha=input('Enter the value of alpha: ');
r=alpha*dt/dx^2;
r2=1-2*r;
% INITIAL CONDITION
t=0;
u=0;
% LOOP OVER TIME STEPS
for m=1:nt
    uold=u;
    t=t+dt;
    % LOOP OVER SPACE STEPS
    for i=2:nx-1
       u(i)=r*uold(i-1)+r2*uold(i)+r*uold(i+1);
    end
end