why doesn't this matlab code work? HELP!!!

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Erika Abril
Erika Abril 2021-3-6
评论： Walter Roberson 2021-3-7
My problem is that this code doesn't work and I need the graph. Help please.
clear all
clc;
es=0.007;%m
d=2800;%kg/m^3
k=180;%W/m K
E=0.8;
C=900;%J/kg K
Tamb=298;%K
As=0.04;%m^2
qh=12500; %W/m^2 K
h=10;%W/m^2 K
Tfp=408;%K
cteEB=5.67*10^-8;
V=0.00028;%m^3
to=0;
deltat=0.1;% seconds
t=[];
Tf=[];
while (Tfp>=Tf)
Tf(i+1)=(As/(d*C*V))*(qh-(h*(Tf(i)-Tamb))-(E*cteEB*(Tf(i)^4-Tamb^4)))*deltat+Tf(i);
t(i+1)=t(i)+deltat;
hold on
plot(Tf,t);
i=i+1;
end
xlabel ('Temperature');
ylabel ('Time [s]');
  2 个评论
John D'Errico
John D'Errico 2021-3-6
PLease do not provide a PICTURE of your code. That makes it virtually impossible for someone to easily help you, because they need to then type in your code by reading the code and then transcribing it character by character into MATLAB. And why would you possibly want to make it more difficult to get help?
Erika Abril
Erika Abril 2021-3-6
clear all
clc;
es=0.007;%m
d=2800;%kg/m^3
k=180;%W/m K
E=0.8;
C=900;%J/kg K
Tamb=298;%K
As=0.04;%m^2
qh=12500; %W/m^2 K
h=10;%W/m^2 K
Tfp=408;%K
cteEB=5.67*10^-8;
V=0.00028;%m^3
to=0;
deltat=0.1;% seconds
t=[];
Tf=[];
while (Tfp>=Tf)
Tf(i+1)=(As/(d*C*V))*(qh-(h*(Tf(i)-Tamb))-(E*cteEB*(Tf(i)^4-Tamb^4)))*deltat+Tf(i);
t(i+1)=t(i)+deltat;
hold on
plot(Tf,t);
i=i+1;
end
xlabel ('Temperature');
ylabel ('Time [s]');

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采纳的回答

Walter Roberson
Walter Roberson 2021-3-6
编辑：Walter Roberson 2021-3-7
You did not initialize i so it will have its default value of sqrt(-1). Then inside the loop when you assign to Tf(i+1) that is a destination of 1+1i which is not a valid index.
For that code to work you need to initialize i to 1.
  1 个评论
Walter Roberson
Walter Roberson 2021-3-7
Tf=[];
while (Tfp>=Tf)
You initialize Tf to empty. When you compare Tfp to empty, the result is false, so your while loop never executes.

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更多回答（1 个）

Basil C.
Basil C. 2021-3-6
The error could be in the while loop. Try using the following.
while(Tfp>=Tf(end))
If you could share the error, it would be more helpful
  2 个评论
Walter Roberson
Walter Roberson 2021-3-6
Oddly enough in this particular loop testing the entire vector is not the problem, though testing an entire vector is often a problem.
Erika Abril
Erika Abril 2021-3-6
The problem is the graph, the code doesn't work :(

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