Attempted to access x(402); index out of bounds because numel(x)=401.

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I want to apply forward downstream scheme on a linear advection equation; this code was used in forward upstream scheme and I could not modify it to fit my application.
The error is caused by the "k+1" in line 18 of the code
dx = 0.05; dt = 0.01; C = 1; A1 = 1-C*dt/dx; A2 = C*dt/dx;
x = [0:dx:20];
N = length(x);
for k = 2:N
if (x(k) >= 4) && (x(k) <= 6)
u(k) = cos(0.5*pi*(x(k)-5));
else
u(k) = 0;
end
end
u(1) = u(N);
for k = 1:N
uplot(1,k) = u(k);
end
for iout = 1:5
for n = 1:5
for k = 2:N
u1(k) = A1*u(k)+A2*u(k+1);
end
u1(1) = u1(N);
for k = 1:N
u(k) = u1(k);
end
end
for k = 1:N
uplot(iout+1,k) = u(k);
end
end

Accepted Answer

Stalin Samuel
Stalin Samuel on 10 Jan 2015
instead of N use N-1

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