find is not matching a value of 1 in an array

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Jeremy Quandt
Jeremy Quandt 2020-3-19
评论： Jeremy Quandt 2020-3-19
I am unable to match a value of 1 with find when checking an array produced by linspace. Is this as expected behavior?
% Create our k samples.
k = linspace(0.1, 2.0, 20)
% Find indexes.
[find(k==0.5) find(k==1.0) find(k==1.5)]

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采纳的回答

Adam Danz
Adam Danz 2020-3-19
编辑：Adam Danz 2020-3-19
This is due to roundoff error.
Here's a demo showing the roundoff error.
k = linspace(0.1, 2.0, 20); % 1 is in positon 10
k(10) - 1
ans =
-1.1102e-16
Here are alternatives.
% find the value of 1
idx = find(ismembertol(k,1));
or
% find the value of 1
[~, idx] = min(abs(k-1))

更多回答（1 个）

Loren Shure
Loren Shure 2020-3-19
You are running into an issue of floating point arithmetic. You might use ismembertol : mathworks.com/help/matlab/ref/ismembertol.html

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