MATLAB: Find function cannot find the value

comparing floating point numbersfind

Hello, I'm trying to use find function to find the value for example from a data with: data = [0, 1.00 2.00 3.00 4.00]; float values for example, if I do:

[~,indx] = find(data == 1.00),

the result would be an empty cell, []. Why is this the problem?

Best Answer

It works fine:

data = [0, 1.00 2.00 3.00 4.00]; 
[~,indx] = find(data == 1.00)

In the command window:

indx =
   2

I suspect your numbers aren't EXACTLY that and what you're running into is this: http://matlab.wikia.com/wiki/FAQ#Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero.3F

Related Solutions

MATLAB: 0x1 matrix getting while using find function

My best guess here, with the limited information you have given, is that you are trying to compare a number to one that is not exactly equal, due to floating point representation.

Take a look at this question/answer for more details.

MATLAB: Build 2-D array with same 1-D array

hi Renuyan

yes, MATLAB has repmat

A=[1 2 3 4 5 4 6]

you set the amount of repetitions

reps=5

to replicate vertically:

repmat(A,reps,1)=
    1.00          2.00          3.00          4.00          5.00          6.00
    1.00          2.00          3.00          4.00          5.00          6.00
    1.00          2.00          3.00          4.00          5.00          6.00
    1.00          2.00          3.00          4.00          5.00          6.00
    1.00          2.00          3.00          4.00          5.00          6.00

replicating horizontally:

repmat(A,1,reps)=
  Columns 1 through 7
 1.00        2.00        3.00        4.00        5.00        6.00        1.00
  Columns 8 through 14
 2.00       3.00         4.00        5.00        6.00        1.00        2.00
  Columns 15 through 21
 3.00       4.00         5.00        6.00       1.00         2.00        3.00
  Columns 22 through 28
 4.00      5.00          6.00        1.00       2.00        3.00         4.00
  Columns 29 through 30
 5.00          6.00

so far the answer, but in similar exercises you may find also useful the command reshape. Let's say you want to stack A, either

reshape(A,[6,1]) =
          1.00
          2.00
          3.00
          4.00
          5.00
          6.00

If you find this answer of any help solving your question, please click on the thumbs-up vote link,

thanks in advance

John

jgb2012@sky.com

Best Answer

Related Solutions

MATLAB: 0x1 matrix getting while using find function

MATLAB: Build 2-D array with same 1-D array

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