Keep getting error message for polyfit

I'm following a tutorial for an example out of a textbook, I've copied the instructors code exactly but keep getting an error message

My code:

x = 0:0.3:1.8;
y = [.5 .6 .8 1.3 2 3.2 4.8];
plot(x, y, 'b-*')
f = fit(x',y', 'poly2');

error message:

Check for missing argument or incorrect argument data type in call to function 'fit'.

Error in Week_9 (line 6)

f = fit(x',y', 'poly2');

I can't find the error in my code

[Walter Roberson]

Do you have the Curve Fitting Toolbox licensed and installed?

[dpb]

What does

which -all fit

return?

Answer 1

[Image Analyst]

Try polyfit() and polyval()

x = 0:0.3:1.8;
y = [.5 .6 .8 1.3 2 3.2 4.8];
plot(x, y, 'b-*', 'LineWidth', 5)
coefficients = polyfit(x(:),y(:), 3);
f = polyval(coefficients, x);
hold on;
plot(x, f, 'ro-', 'LineWidth', 2, 'MarkerSize', 15);
grid on;
legend('y', 'f');