# Matlab cannot Produce graph

1. Oct 14, 2013

### iwan89

1. The problem statement, all variables and given/known data

2. Relevant equations
This are the program

L = 1.;
T = 1.;
maxk = 2500;
dt = T/maxk;
n=50;
dx = L/n;
cond = 1/4;
b = 2.*cond*dt/(dx*dx);
for i= 1:n+1
x(i) = (i-1)*dx;
U(i,1) = sin(pi*x(i));
end
for k=1:maxk+1
u(1,k) = 0.;
u(n+1,k)=0.;
time(k) = (k-1)*dt;
end
for k=1:maxk
for i=2:n;
u(i,k+1)=u(i,k)+0.5*b*(u(i-1,k)+u(i+1,k)-2.*u(i,k));
end
end
figure (1)
plot (x,u(:,1),'-',x,u(:,100),'-',x,u(:,300),'-',x,u(:,600),'-')
title ('Temperature within the explicit method')
xlabel ('X')
ylabel ('Y')
figure (2)
mesh (x,time,u')
title ('Temperature within the explicit method')
xlabel ('X')
ylabel ('Temperature')

3. The attempt at a solution
The program works but i cant produce any graph. I think there are little mistake somewhere.. :( pls help me

2. Oct 14, 2013

### Office_Shredder

Staff Emeritus
I think your problem is this line here

which should have a u(i,1) instead of a U(i,1)

3. Oct 14, 2013

### iwan89

Thank you so much :) really appreciate it :)
1 more thing
how can i tabulate data from the graph?

4. Oct 14, 2013

### Office_Shredder

Staff Emeritus
I don't really understand your question (are you asking how to use the tabulate function in matlab?). At any rate you should make a new thread if you have a new question.

5. Oct 14, 2013

### iwan89

ok :) i will post a new question