Finding the index of spesific element in a matrix?

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IBM watson
IBM watson le 23 Mai 2019
Commenté : Ulika Naidoo le 22 Jan 2021
Lets say we have matrix:
a=[ 2, 3, 5
3, 4, 7
4, 4, 4] ;
I want to know index of a(4) which is the bold 3. This is just an example. I want to learn how to find index of a(n).

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madhan ravi
madhan ravi le 23 Mai 2019
Modifié(e) : madhan ravi le 23 Mai 2019
Assuming you want to index of the last match in the matrix:
Index=find(a==3,1,'last')
  13 commentaires
madhan ravi
madhan ravi le 23 Mai 2019
Modifié(e) : madhan ravi le 23 Mai 2019
No problem, by the way the original question you asked is totally irrelevant to your latter comment. Please don’t do this in the future riddling the answers.
Look into ind2sub() function to convert the linear indices. To understand what this statement means , you need to read the link which I shared thoroughly and practice. And finally have a look at ind2sub().
IBM watson
IBM watson le 23 Mai 2019
Sure, I didn't do it on purpose. Just could't explain clearly what I want. Thanks again.

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KALYAN ACHARJYA
KALYAN ACHARJYA le 23 Mai 2019
Modifié(e) : KALYAN ACHARJYA le 23 Mai 2019
I want to know index of a(4) which is the bold 3
here ......................... this 4^ represent the index, I guessing you are looking for following one.
idx=find(a==3);
One dimentional case array case
>> a=[2,3,5,3,4,7,4,4,4];
>> idx=find(a==7)
idx =
6
>> idx=find(a==3)
idx =
2 4
But Matrices have 2 dimention so indices represents (x,y), where answer will be little different
>> a=magic(3)
a =
8 1 6
3 5 7
4 9 2
>> [r c]=find(a==3)
r =
2
c =
1
  5 commentaires
Stephen23
Stephen23 le 5 Mar 2020
"why c =1 ? "
Because the value 3 is in the 1st column.
Ulika Naidoo
Ulika Naidoo le 22 Jan 2021
Thank you!

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