Find minimum of single-variable function

Hi, what expression is calculated by the following command in Matlab?

Code:

fminbnd(@(x) (sin(x).^2-1),0,pi)

Minimum of:

(a) f(x)=1-sin x^2 or (b)1-sin^2x.

I answered a) in my exercise, however I am not sure if this is correct. Can someone tell me if this is correct?

[Adam Danz]

Sounds like homework.

The documentation should be helpful to understand what that function is doing,

https://www.mathworks.com/help/matlab/ref/fminbnd.html

[Mark S]

Thank you for your help. I have answered a) in my exam, it would be nice if you can say if it's right or not. Because also with the link that you have mentioned i am not sure if my answer was right or not :/

Answer 1

[Adam Danz]

Hint:

[x,fval] = fminbnd(___)

gives you the (x,y) values at the minimum.

You could plug the x values into both of your options and the one that returns the matching y value is the correct function.

[Mark S]

Ok, for x i get 4.5994e-05 and for fval =-1.0000

I put x into a) f(x)=1-sin4.5994e-05^2=1

I put x into b) f(x)=1-sin^2 *4.5994e-05=1

I get for same 1. But I think this cant't be right...

[Adam Danz]

Could you share the 2 lines of code where you tested the two versions? There's probably an error in how you're setting the equations.