How to trim(remove) plot

I should remove yellow there, and get a maximum of x (when y = 0)

and there's no x-intercept

I tried :

if y < 0, y = [] else plot(x, y)

mask = (y<0) cla(mask)

interp1(y, x, 0) => it comes to zero

but any of them didn't work.

if I can cut off that part, I can get the answer : [ k, l ] = find(x==max(x)) x_int = [ max(x) , y(k, l) ] .

How can I trimming that part?

Answer 1

[DGM]

Try something like this:

x=0:300;
y=-0.008*x.^2 + 2*x + 1.5;
y(y<0)=NaN;

Anything that's NaN won't be plotted.

Alternatively, you can do it the way you were trying:

mask=y>=0;
y=y(mask);
x=x(mask);

and then your intercept finding method should work.

intercept=[x(end) y(end)]

Intercepts could also be found symbolically.

[AhyounLee]

OMG THX YOU

It really helped me thanks