No graphs after plot command

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semiha
semiha on 15 Feb 2015
Commented: semiha on 15 Feb 2015
Hello everybody; I have a question about plot command. When i run the script, there is no error message but empty figure has appeared. I couldn't solve this problem using gcf or noFigure = 1; figure(noFigure); command. What should i do to see the graph? Thanks for your help
  2 Comments
Geoff Hayes
Geoff Hayes on 15 Feb 2015
Semiha - what is the script that you are using? What code is being used to plot something to the figure? Please provide more details.
Star Strider
Star Strider on 15 Feb 2015
semiha’s ‘Answer’ moved here ...
a = 100;
m = 1000;
n = 1000;
h = a/m;
t1 = 100;
k = t1/n;
x = 0:h:a;
t = 0:k:t1;
D = -k;
w0 = zeros(1,m+1);
w = zeros(n+1, m+1);
A = zeros(m+1, m+1);
B = zeros(m+1, m+1);
for j = 1:m+1
w0(j) = (1-(5*(1-3*i))/((1+6*(x(j)^3))));
end
w(1,:) = w0;
for p=1:n
for j=1:m+1
A2 (j)= k*1*i;
A(j,j) = A2(j);
end
for j=1:m
A(j,j+1) = 1 - 1i*D*abs(w(p,j)).^2;
end
for j=1:m-1
A(j,j+2)=k*1*i;
end
A(m,m)=k*1*i;
A(m,1)= 1 - 1i*D*abs(w(p,j)).^2;
A(m,2)=k*1*i;
A(m-1,1)=k*1*i;
A(m-1,m)= 1 - 1i*D*abs(w(p,j)).^2;
A(m-1,m-1)=k*1*i;
r =(A)*w(p,1:m+1)';
w(p+1,1:m+1)=r';
end
plot3 ( x, t,(abs(w(n,:))) );

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Answers (1)

emehmetcik
emehmetcik on 15 Feb 2015
Your output variable "w" mostly consists of "nan" (not a number) values. Probably the result of zero divided by zero at some point.
Only the first few rows of "w" have no nan's.
  3 Comments
emehmetcik
emehmetcik on 15 Feb 2015
I'm not quite sure what the code does. But the problem seems to be that some values grow exponentially.
My recommendation is that you should re-check your code. The following commands can be useful as well:
dbstop if naninf
This will automatically put a debug point when a nan or inf value is encountered while the code is being executed.
dbclear all % To clear all debug points
semiha
semiha on 15 Feb 2015
yes you are right i used dbstop if naninf command, it seems that one line creates this situtation. ( A(j,j+1) = 1 - 1i*D*abs(w(p,j)).^2) i should use this line to get a correct answer, but i will try to change it. Thanks

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