MATLAB: Am I getting this error? ‘Unrecognized function or variable ‘poly2str’.’

MATLAB and Simulink Student Suitepoly2str

Every time I use the 'poly2str' function Matlab is saying its an unrecognized function or variable. I am following video tutorials on matlab basics and the code I am using has been provided by my lecturer, and he uses the exact same code in the video without any problems. The only thing is that the videos could be outdated as they are a few years old, so maybe is that the issue?
figure(2); clf reset
x2=-3:.1:5;
p=poly([-1 -2]);
px = polyval(p,x2);
plot(x2,px,'r:')
title(['Plot of polynomial with coefficients ',num2str(p)])
xlabel('x')
ylabel(poly2str(p,'x'))

Best Answer

I first tried poly2sym, and although it works, it does not print out correctly with anything I tried. (It prints as 3*x + x^2 + 2.)
So I went with the obvious: 
figure(2)
x2=-3:.1:5;
p=poly([-1 -2]);  
px = polyval(p,x2);
plot(x2,px,'r:')
title(['Plot of polynomial with coefficients ',num2str(p)])
xlabel('x')
polysym = poly2sym(p,sym('x'));
ylabel(sprintf('x^2 + %dx + %d',p(2:3)))
I left in the poly2sym call in case you want to experiment with it.
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