How can I plot a sym variable?

I am trying to plot a function and it's derivative, but

syms x y

y=4*x*cos(x)+2*x^cos(x^2)

dydx=diff(y)

plot(y)

gives me an error that I cannot convert double to sym. I know I can plot a function and its derivative using LINSPACE but I want the analytical derivative value as well. How can I plot y and dydx? I also know I can use "EZPLOT" but that doesn't let me do very much with the plotter. Is it possible to plot a symbolic variable and if it is now, how do I get an analytical derivative AND plot it in MatLab?

[Walter Roberson]

The analytic derivative will be a formula, and you cannot plot() a formula. You could put the formula up as text using text()

Answer 1

[Youssef Khmou]

hi did you try this :

 syms x y dy
 y=4*x*cos(x)+2*x^cos(x^2)
 dy=diff(y,1);
 figure, ezplot(y); hold on; ezplot(dy);

[Kavan]

yes, but I don't want to use EZPLOT because I can't change the color of the plot

[Youssef Khmou]

and if you move back to numeric ? fine ?

xAxis=[0:0.1:10];
Y=subs(y,xAxis);
DY=subs(dy,xAxis);
figure, plot(Y), hold on, plot(DY,'r')