Plotting in Octave

Question

I would like to plot the following function

        norm(A-x*eye(3),2) 

on the interval -1 < x < 1, where A is a fixed 3x3 matrix. Somebody has an idea how can I do this?

Answer 1

x = linspace(-1, 1, 100); % plot 100 points
y = arrayfun(@(x) norm(A-x*eye(3), 2), x);
plot(x,y);

Answer 2

fplot(@(x) norm(A-x*eye(3),2),[-1,1])