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

help

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.

Best Answer

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.
Related Question