How do I get my code to display the associated x values for maximum and minimum

In addition, How do I get it to label the coordinates in the graph it makes? I tried getting it to display Xmax or Xmin, but it says not defined.

a = -7.0;
b = 1.0;
c = 2.0;
d = 20.0;
e = 2.0;
f = 5.0;

p = @(x) c * x.^3 + d * x.^2 + e * x + f;

CP = quadratic(3 * c, 2 * d, e);
 crit_pt1 = CP(1);
 crit_pt2 = CP(2);

if isreal(crit_pt1)
  disp('Crit Point 1:');
  disp(crit_pt1);
  disp('p(Crit Point 1):');
  disp(p(crit_pt1));

    disp('Crit Point 2:');
    disp(crit_pt2);
    disp('p(Crit Point 2):');
    disp(p(crit_pt2));
  else
    disp('The critical points are complex.');
  end

disp('Left Endpoint:');
disp(a);
disp('p(Left Endpoint):');
disp(p(a));

disp('Right Endpoint:');
disp(b);
disp('p(Right Endpoint):');
disp(p(b));
Q=[p(a),p(b),p(crit_pt1),p(crit_pt2)];
disp('p(Xmax):');

disp(max(Q));
disp('p(Xmin):');
disp(min(Q));

delta = (b - a) / 100;
x = a:delta:b;
y = p(x);
plot(x, y)

Answer 1

[Matt J]

You can use the text() command. Or, you can do

set(axis_handle,'XTick',whatever)

to have the x-axis show "whatever".

[cakey]

In whatever, do I put the p(Xmax)? And it says undefined function at axis_handle.

[Matt J]

"whatever' must be a vector of all values you want tick marked on the axis.

axis_handle is not a function call. You need to pass a handle to your plot axis, either as obtained by gca() or some other means.

[cakey]

Yes, I do not understand the language. Is there anywhere where I can read how to do it?

[Matt J]

About axis handles? You can start with "doc gca" and pages that it links to.