Matlab Plotting Error

I'm trying to find the roots for an equation but cannot get the correct answer. I tried plotting the function in Matlab over an interval that would include all roots, but did not get the plot that I would expect for such a function. Also, when using fzero for the function and appropriate guesses, I get incorrect answers for the roots. Upon copying and pasting the same function into another (unnamed) program, I received the correct roots using the same initial guesses. Is there an error in my function syntax or is it in Matlab??

mu=0.01215;

x=[-1:3];

f1= -1*(1-mu).*(x+mu)/((sqrt((x+mu).^2)).^3) - mu.*(x-1+mu)/((sqrt((x-1+mu).^2)).^3) + x;

plot(x,f1)

It plots a linear equation, but it should have oblique and vertical asymptotes.

I wasted about two hours of time trying to find errors on something that should have taken about 10 minutes, only to find out it worked elsewhere.

Answer 1

[Walter Roberson]

You should refine your sampling points.

[-1:3] does not denote a closed interval in MATLAB: it is the same thing as [-1 0 1 2 3] which is only 5 sampling points.

Try

x = linspace(-1,3,50);

[Jason]

I tried it previously to no avail. I know the interval is undefined over a portion of it, but why wouldn't it still plot the points that are defined? Or give me correct answers for the roots?

[Walter Roberson]

Incorrect vectorization. You missed the "." before the "/" in both places.