using fzero with arrayfun searching for zeros inside an interval

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Thomas
Thomas 2020-12-6
评论： Thomas 2020-12-9
I have a function f = @(x) -x.^2+4 with a zero at -2 and +2
using fzero(f, [-3, 1.9]) I get the (correct) zero inside the interval [-3, 1.9] , which is -2
when I now have not one but multiple intervals where I want to detect zeros, let's say: [-3, 1.9] and [1.9, +3],
fzero(f, [-3, 1.9; 1.95, 3]) returns an error, telling me, that the second argument must be scalar or a vector of length 2 (= interval).
When I now try to use arrayfun in order to successively apply my intervals to fzero I get:
arrayfun(@(x) feval("fzero" , f, x), [-3 1.9; 1.95 3])
ans =
-2 2
2 2
because fzero does not take intervals, but single values.
However I would like to use intervals and the expected result should be
-2
2
I do not want to use a for loop because of performance issues.
Now the question: Can anyone help how to make "fzero" run on multiple intervals using "arrayfun" (or any other trick) ?

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采纳的回答

Ameer Hamza
Ameer Hamza 2020-12-6
Create a cell array and then use cellfun()
f = @(x) -x.^2+4;
C = {[-3 1.9]; [1.95 3]};
sol = cellfun(@(x) fzero(f, x), C)

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