Find index of a number in a 3d array

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Baiwen Ding
Baiwen Ding 2022-9-13
编辑： Bruno Luong 2022-9-13
Hi.
I have a 14610x146x220 3d array. I know that somewhere in this array there is a value of 31.5814 however i dont know what is the index of this value. May i know how do i find out what is the index of this value?
Edit:
For me I used the solution from
https://www.mathworks.com/matlabcentral/answers/1804400-find-index-of-a-number-in-a-3d-array#comment_2361320
Thanks all for helping.

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采纳的回答

Torsten
Torsten 2022-9-13
i = find(A(:) == 31.5814);
[i1 i2 i3] = ind2sub([14610,146,220],i(1));
A(i1,i2,i3)
But most probably, floating point inaccuracies will inhit finding the value.
You could try
epsilon = 1e-6;
i = find(abs(A(:)-31.5814)<epsilon);
[i1 i2 i3] = ind2sub([14610,146,220],i(1));
A(i1,i2,i3)
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Baiwen Ding
Baiwen Ding 2022-9-13
Hi thanks for the answer it worked. Do you mind explaining the rationale behind the solution? Thanks.
Bruno Luong
Bruno Luong 2022-9-13
编辑：Bruno Luong 2022-9-13
Just look for the closest point to 31.5814, the metric is d=abs(x-31.5814). This solution doesn't need for fine tuning of the tolerance, so easier to work.

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