Function definition not supported in this context. Create functions in code file.

Below is my code to solve the parallel plate capacitor problem.

clear all

x=linspace(1,20,10);
y=linspace(1,20,10);
[X,Y]=meshgrid(x,y);

C=delaunay(X(:),Y(:));
xy=[X(:) Y(:)];
Np=length(xy);
S=MatGlob(xy,C);
F=sparse(Np,1);

V0=1;
G=1e12;
for k=1:Np;
if x(k)==1
S(k,k)=S(k,k)+G;
F(k)=G*(-V0);
if x(k)==20
S(k,k)=S(k,k)+G;
F(k)=G*(+V0);
end
V=S\F;

figure
plot(xy,V,'*-')
title('potential(V)')
xlabel('postition(m)')
ylabel('postition(m)')
hold on
function S=MatGlob(xy,C)
Np=length(xy);
S=sparse(Np,Np);
Epsr=3.5;
Ne=size(C,1);
for k=1:Ne
    N=C(k,:);
    x1=xy(N(1),1);
    x2=xy(N(2),1);
    x3=xy(N(3),1);
    y1=xy(N(1),2);
    y2=xy(N(2),2);
    y3=xy(N(3),2);
    abc1=[1 x1 y1;1 x2 y2;1 x3 y3]\[1;0;0];
    abc2=[1 x1 y1;1 x2 y2;1 x3 y3]\[0;1;0];
    abc3=[1 x1 y1;1 x2 y2;1 x3 y3]\[0;0;1];
    Grad=[abc1(2) abc2(2) abc3(2); abc1(3) abc2(3) abc3(3)];
    Se=Epsr*(Grad'*Grad)*abs((x2-x1)*(y3-y1)-(x3-x1)*(y2-y1))/2;
    S(N,N)=S(N,N)+Se;
end
end

Yet, Matlab annouce the error as follows: "Function definition not supported in this context. Create functions in code file" Would you please help me to fix this error? Thank you in advance.

[Adam]

What version of Matlab are you using?

Simplest option is to do exactly what the error suggests though - create a new .m file, put the function in there and add it to your path.

[Stephen23]

@Duc Tu Vu: your code is badly aligned. Badly aligned code is one way that beginners hide bugs in their code, just like you have done. You should align your code using the default MATLAB Editor settings. You can also align existing code: select the code and press ctrl+i.

[Mebo Valle]

I am experiencing the same problem, i have tried to align but nothing is happening, its just a simple and small code

function myRand

a=1+rand(3,4)*9

end

using R2019a

[Mebo Valle]

[Adam]

And you are getting the error about function definitions not being permitted in that context or some other problem?

Answer 1

[Steven Lord]

When I Smart Indent your code, I see that the function definition is inside both a for loop and an if statement. That is not allowed. That restriction is explicitly stated in the documentation listing the requirements for nested functions. While that restriction is not explicitly stated in the documentation for local functions in a script file, it holds for those functions as well. You can see this by hovering over the function keyword underlined in red (indicating a Code Analyzer error) in the Editor and asking for more details.

You also have one too few end keywords in the code you posted, though that may be the result of accidentally omitting the trailing end in your code when you copied and pasted it into Answers. When I add two end statements prior to the function definition and ran the code, I saw a plot but it threw an error as well. I recommend checking lines 6 and 7 of your code to make sure they're doing what you want them to do. As a hint, the size function may be of use to you.

Answer 2

[Duc Tu Vu]

Thank all for the help. I have already solved this problem.

[WHISKY Chen]

How did you solve that problem? Could you please help me!

I have the same problem and... haven't solved it.

[egg]

same here!

[Steven Lord]

Try smart indenting your code to determine if you're trying to define a nested function inside an if, for, while, etc. statement (which is not allowed.)

Also make sure you're using release R2016b or later. The ability to define functions in scripts was introduced in release R2016b and will not work in earlier releases.

[Naireeta Deb]

It doesn't work :/

[Steven Lord]

Without more information about what you're doing (and ideally a small example with which you can reproduce the error) it's unlikely we'll be able to give you a more specific suggestion than what I did in my comment immediately before yours.

Make sure you're using release R2016b or later and make sure you're not trying to define the function inside an if, for, while, etc. statement (and you're not trying to define it by typing "function myoutput = ..." at the prompt in the Command Window.)