Error using plot. Vectors must be the same length.
显示 更早的评论
Hello,
When running my code I'm getting the following error :
Error using plot
Vectors must be the same length.
Error in A5Q2 (line 45)
plot(x1,u(1,:),'*',x1,us1,'-');
Please find below my code:
function u = diff1_ex
ngrid = 50;
dx = 1/ngrid;
D=1;
s=0.4;
dt = s*dx^2/D;
tmin=0;
tmax=1;
ntime = ceil((tmax-tmin)/dt);
u = zeros(ngrid+1,ntime);
source=1;
for l=1:ntime
for k=2:ngrid
u(k,l+1)=u(k,l)+s*(u(k+1,l)-2*u(k,l)+u(k-1,l));
if (k>ceil((0.4/dx)-1)) && (k<ceil(0.6/dx))
u(k,1+l)=u(k,1+l)+ dt*source;
end
end
end
subplot(2,1,1);
imagesc(u);
colorbar;
xlabel('x')
ylabel('y')
x1 = 0:dx:1;
us1 = -0.3*x1;
x2 = 0.4:dx:0.6;
us2 = (-x2.^2)/2+(0.1*x2)-0.08;
x3 = 0.6:dx:1;
us3 = 0.5*(1-x3);
subplot(2,1,2);
hold on
plot(x1,u(1,:),'*',x1,us1,'-');
plot(x2,u(2,:),'*',x2,us2,'-');
plot(x3,u(3,:),'*',x3,us3,'-');
hold off
xlabel('x')
ylabel('us')
title('Stationary Solution')
Could you please help me to correct my mistake.
Please find attached the questions and my solution to the first question.
Thanks in advance
5 个评论
dpb
2018-10-28
Use the debugger and set a breakpoint after the line
u = zeros(ngrid+1,ntime);
look at
whos u
then at the plot() line try
length(u(1,:))
Vashist Dwarka
2018-10-28
dpb
2018-10-28
When the debugger prompt shows up, type it in at the prompt.
See
doc whos
PS: By "at the plot line" I meant either set another breakpoint at that line and run until there or just step through until you get there (F10)
Vashist Dwarka
2018-10-28
Basically you just click on the line where you want a breakpoint in the editor and then press RUN since your function doesn't require any input arguments.
As a hint to your problem, look at how you defined the array u and then how you try to use it when you are trying to plot.
Learning to use the debugger is well worth the effort...
回答（2 个）
madhan ravi
2018-10-28
plot(x1,u(1,1:numel(x1)),'*',x1,us1,'-');
plot(x2,u(2,1:numel(x2)),'*',x2,us2,'-');
plot(x3,u(3,1:numel(x3)),'*',x3,us3,'-');
4 个评论
madhan ravi
2018-10-28
maybe like the above? not sure if its correct
Vashist Dwarka
2018-10-28
madhan ravi
2018-10-28
ok then no idea because your x1, x2, x3 size is 1 by 51 and your u size is 51 by 6251 , how can you plot them?
Vashist Dwarka
2018-10-28
类别
在 帮助中心 和 File Exchange 中查找有关 Get Started with MATLAB 的更多信息
2018-10-28
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
Translated by 
