I want to use fzero to do so, but I don't know how, since x is a matrix, rather than a symbolic function.
How to find zeros of a function?
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For instance,
x = -3.55:0.1:3.55;
y = x.^2 - 4;
Obviously, when x=2 or -2, y=0.
But I want to know how to use matlab to find zeros of a function y = f(x) when x is a matrix defined by the user like the above case.
3 Comments
Mark Sherstan
on 17 Dec 2018
Akira Agata
on 17 Dec 2018
If your function is always polynomial, you can use roots function to do this task. Please look at the following help page.
Answers (3)
Wenjie
on 17 Dec 2018
3 Comments
Nico
on 25 Feb 2024
What does the @(x) and the 3 mean? Sorry I'm university student with no experience...
Alexander
on 25 Feb 2024
If it's not a function but meassured data I would go like this in a first try:
x = -3.55:0.0001:3.55; % assuming 10 kHz sample frequency
y = x.^2 - 4;
yS = sign(y);
dyS = diff(yS);
Z=find(dyS ~= 0);
x(Z)
Walter Roberson
on 17 Dec 2018
x(y==0)
Note that this can miss an indefinite number of zeroes of a function if the x do not happen to sample at the right places . It also will not detect zero crossings between x values . You could make use of the results to get hints about zero crossings .
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