Finding location of specific element from a MATRIX returns '0×1 empty double column vector'

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Zhou Ci 2021-9-23

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https://ww2.mathworks.cn/matlabcentral/answers/1459044-finding-location-of-specific-element-from-a-matrix-returns-0x1-empty-double-column-vector

评论： Zhou Ci 2021-9-23

采纳的回答： Chunru

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Hi everyone,

I have a matrix and I'm trying to find location of some specific elements but it gives me no answer. My code:

[i,j] = find(a==23.5975) % it can be clearly seen in the figure that this value is present in the 
% 1st row and 3rd column. but it gives the following result. 
i =
  0×1 empty double column vector
j =
  0×1 empty double column vector
  

I'll be gratefu for any help, thank you.

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采纳的回答

Chunru 2021-9-23

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https://ww2.mathworks.cn/matlabcentral/answers/1459044-finding-location-of-specific-element-from-a-matrix-returns-0x1-empty-double-column-vector#answer_793404

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[i,j] = find(abs(a-23.5975)<1e-20)

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Walter Roberson 2021-9-23

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target = 0.1863
target = 0.1863
rng(1);
a = rand(4)
a = 4×4
    0.4170    0.1468    0.3968    0.2045
    0.7203    0.0923    0.5388    0.8781
    0.0001    0.1863    0.4192    0.0274
    0.3023    0.3456    0.6852    0.6705
[found, idx] = ismembertol(target, a)
found = logical
   0
idx = 0
[~, minidx] = min(abs(target - a(:)));
a(minidx)
ans = 0.1863
a(minidx) - target
ans = -3.9789e-05
[found, idx] = ismembertol(target, a, 1e-4)
found = logical
   1
idx = 7

Zhou Ci 2021-9-23

Working now, Thanks alot!

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MATLAB Language Fundamentals Matrices and Arrays Creating and Concatenating Matrices

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