Need help finding intersection of two curves using fzero function

I'm new to MatLab (just started using it 2 days ago), and currently my goal is for the program to spit out the values of the points of intersections of two curves using the fzero command. This is my code:

syms x

y1 = x^8;

y2 = power(4,x);

f(x) = y1-y2;

fzero (f,-0.86)

The x value of the point of intersection is supposed to be x=-0.861345, however when I enter this code in, it outputs

ans =

-0.8357

, which isn't the correct value. When I change the value of the number inside the fzero command, it outputs a different number each time. How do I fix this? Thank you.

Answer 1

[Star Strider]

With symbolic variables, use the vpasolve function:

syms x
y1 = x^8;
y2 = power(4,x);
f(x) = y1-y2;
intersection = vpasolve(f)

producing:

intersection =
-0.8613453323096513195240262391528

To use fzero, first use the matlabFunction function to create ‘f’ as an anonymous function (here):

ffcn = matlabFunction(f)
intersection = fzero(ffcn, -1)

producing:

intersection =
  -0.861345332309651

Experiment to get the result you want.

[Syam Angalakuditi]

Thank you very much for the detailed answer! The assignment requires that i use the fzero command to do the problem so I will be using that one.

[Star Strider]

As always, my pleasure!