Issue with find()

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.

Answer 1

[KSSV]

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

[David]

That works fine too, thank you very much!