How to assign a constant to a submatrix without a loop

Question

Ben Kaye 2020-4-29

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/521747-how-to-assign-a-constant-to-a-submatrix-without-a-loop

编辑： Adam Danz 2020-5-4

Is this possible without a for loop? Sample code:

%A is an (m x n) matrix m,n > 2
A(2:end-1,2) = 67.5*ones(size(A(2:end-1,2)));

I so far can not make this work.

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Adam Danz 2020-4-29

编辑：Adam Danz 2020-4-30

在 MATLAB Online 中打开

What's the problem with the code in your question other than that it can be simplified (see answer)?

A =
     5     4     9     2     8     8
     1     6     1    10     7     3
     2     5     8     4     4     8
     8     6     1    10     9     6
     6     9     3     2     5     7
>> A(2:end-1,2) = 67.5*ones(size(A(2:end-1,2)))
A =
            5            4            9            2            8            8
            1         67.5            1           10            7            3
            2         67.5            8            4            4            8
            8         67.5            1           10            9            6
            6            9            3            2            5            7

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Answer 1

Adam Danz 2020-4-29

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/521747-how-to-assign-a-constant-to-a-submatrix-without-a-loop#answer_429201

编辑：Adam Danz 2020-5-4

在 MATLAB Online 中打开

A = magic(9)  % demo matrix
A(2:end-1,2) = 67.5; 

result

A(2:end-1,2) = 67.5
A =
           47           58           69           80            1           12           23           34           45
           57         67.5           79            9           11           22           33           44           46
           67         67.5            8           10           21           32           43           54           56
           77         67.5           18           20           31           42           53           55           66
            6         67.5           19           30           41           52           63           65           76
           16         67.5           29           40           51           62           64           75            5
           26         67.5           39           50           61           72           74            4           15
           36         67.5           49           60           71           73            3           14           25
           37           48           59           70           81            2           13           24           35