How to include function in legend

I tried all possibl string2functions of Matlab, but not getting quiete the result.

Here's my best try:

syms x

F = x^2; % Definied Function

g = matlabFunction(F); 

% some random steps 

x = -10:0.1:10;

f = g(x); 

p1 =  plot(x,f);

hold on

n = 20; 

C = jet(n);
for k= 1:n
p2 = plot(x,f+2*k,'Color',C(k,:));
end 

% Here comes the questionable part. 

legend([p1,p2],{strcat('f = ',char(F)),sprintf('f at n =  %0.f',n)},...
    'Interpreter','latex','FontSize',20)

Basically I want the function that I definied to be automatically updated in legend. (Pretty handy if you change f multiple times). However in my attemp I get a warning:

String scalar or character vector must have valid interpreter syntax:

f:x^2

How can the function be acknowledged by the interpreter?

Answer 1

[Star Strider]

A sllightly different approach —

syms x
F = x^2; % Definied Function
g = matlabFunction(F); 
% some random steps 
x = -10:0.1:10;
f = g(x); 
p1 =  plot(x,f);
hold on
n = 20; 
C = jet(n);
for k= 1:n
p2 = plot(x,f+2*k,'Color',C(k,:));
end 
% Here comes the questionable part. 
legend([p1,p2],{sprintf('$f = %s$',char(F)),sprintf('$f\\ at\\ n =  %0.f$',n)},...
    'Interpreter','latex','FontSize',20)

.

[Niklas Kurz]

I reckognized 'latex(F)' instead of 'char(F)' is just more accurate at displaying functions like But either way it is working now! Just the right tweeking.

[Star Strider]

Great!

Thank you!

Answer 2

[Joseph Cheng]

do you need to use latex as just using the default tex? as latex uses $ for markup of symbols i don't know if it'll take the syms function very well without some edits. if you get rid of the interpreter setting and use the default one

syms x
F = x^2; % Definied Function
g = matlabFunction(F); 
% some random steps 
x = -10:0.1:10;
f = g(x); 
p1 =  plot(x,f);
hold on
n = 20; 
C = jet(n);
for k= 1:n
p2 = plot(x,f+2*k,'Color',C(k,:));
end 
% Here comes the questionable part. 
legend([p1,p2],{strcat('f = ',char(F)),sprintf('f at n =  %0.f',n)},...
    'FontSize',20)

more info can be found here in another matlab tex vs latex answers sub

[Niklas Kurz]

Well, latex just looks more beautiful in my eyes :$