Issue with find()

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David
David 2016-9-14
评论： David 2016-9-14
Hello,
I have something that seems to be quite a fundamental issue yet I am having issues fixing it:
I have an array containing various values, and I wish to find where in the array matches a value, which is caclulated eslewhere in the script.
Yet when using find() I'm getting some funny behaviour, as say I know one of the values is 0.65, and the variable containing 0.65 is called ratio_x, using
x = find(array == ratio_x)
returns an empty matrix, yet when using the value itself such as
x = find(array == 0.65)
it works fine.
Both array and ratio_x are saved as double, and array is rounded to 2 decimal places.
Any help would be appreciated.

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KSSV
KSSV 2016-9-14
It is not advised to compare floating point numbers using ==. You have to fix a small number (tolerance) say, eps = 10^-5 and check for is the absolute difference less then that. If so then the floating point numbers are close enough. '
More on:
http://in.mathworks.com/matlabcentral/answers/74074-how-to-find-the-position-index-of-a-floating-point-number-in-matrix
  1 个评论
David
David 2016-9-14
That works fine too, thank you very much!

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