changing values in a certain column of a matrix

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Evelyn
Evelyn 2014-5-4
移动：DGM 2025-10-2，4:59
I have a large matrix and in the fifth column I want to replace every value of 990 with 30.375, how could I do this easily? I found many similar questions but not exactly the same one and I tried to adapt the solutions to my situation but it hasn't worked yet..
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YAHAYA
YAHAYA 2025-10-1，20:25
移动：DGM 2025-10-2，4:59
how can i chage the value first value of the matrix to 0.5, give A(2
2
3)
DGM
DGM 2025-10-2，4:59
Ran in:
See also:
https://www.mathworks.com/help/matlab/math/array-indexing.html
https://www.mathworks.com/help/matlab/math/indexed-assignment.html
https://www.mathworks.com/help/matlab/math/detailed-rules-about-array-indexing.html
For example, assigning an entire row or column using a vector of equal length:
A = magic(4) % we have a 4x4 matrix
A = 4×4
16 2 3 13 5 11 10 8 9 7 6 12 4 14 15 1
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A(3,:) = [2 4 6 8] % assign values to a row
A = 4×4
16 2 3 13 5 11 10 8 2 4 6 8 4 14 15 1
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A(:,3) = [2 4 6 8] % assign values to a column
A = 4×4
16 2 2 13 5 11 4 8 2 4 6 8 4 14 8 1
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For another example, use linear indexing to assign a value to the nth element:
A(6) = 100 % ordering is column-major
A = 4×4
16 2 2 13 5 100 4 8 2 4 6 8 4 14 8 1
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Cedric
Cedric 2014-5-4
编辑：Cedric 2014-5-4
First, you build a logical index of all values equal to 990 in column 5:
lId = A(:,5) == 990 ;
Then you use it to index relevant elements of A (in column 5), that you set to 30.375:
A(lId,5) = 30.375 ;
Let me know if you need more information.
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Cedric
Cedric 2014-5-4
Thank you Image Analyst! Yes, I could have warned, but I always thought that I would be able to come back "within a few days", and I lost track of time!
Dogiparthi Santhosh Gupta
Dogiparthi Santhosh Gupta 2021-4-4
Is the same logic applicable on a table with single column.
My problem is 'I have to replace the values of 2,3,4 in a single column of a table to 1' I tried with your logic but getting an error. Kindly suggest the perfect logic by anyone.

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