# Matlab cannot Produce graph

## Homework 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')

## The Attempt at a Solution

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

Related Calculus and Beyond Homework Help News on Phys.org
Office_Shredder
Staff Emeritus
Gold Member
I think your problem is this line here

U(i,1) = sin(pi*x(i));
which should have a u(i,1) instead of a U(i,1)

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

Office_Shredder
Staff Emeritus