How to get column function result into separate variables?

2018 10 14
2 个回答
更新时间：2018 10 14
2 次查看（30 天）

1 个投票

What I mean is you can do:
A=rand(2);
[a,b]=size(A);
But is it possible to do something like:
A=rand(2);
[a;b]=size(A)';

1 个评论
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Stephen23
Stephen23 2018-10-14
编辑：Stephen23 2018-10-14
"How to get column function result into separate variables?"
The question is not clear. The output of size as you are using it with two output arguments is NOT one "vector", it is two output arguments which have absolutely no dimensional/positional/... relationship with each other. Definitely NOT one "vector" or array as you seem to assume:
[a,b]=size(A);
^^^^^ This is NOT a row vector!
https://www.mathworks.com/help/matlab/matlab_prog/comma-separated-lists.html
https://www.mathworks.com/matlabcentral/answers/320713-how-to-operate-on-comma-separated-lists

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回答（2 个）

KALYAN ACHARJYA
KALYAN ACHARJYA 2018-10-14
编辑：KALYAN ACHARJYA 2018-10-14

0 个投票

But is it possible to do something like:
No, size(X) returns the row vector [1 1].
A=rand(2);
[a;b]=size(A)';
If you tried this one [a;b], it is vector [2,1]
This see the example, you can do this one, this way
>> [a b]=size(A);
>> t=[a b]'
t =
2
2
[m,n]=size(X) returns the size of matrix X in separate variables m and n, here you can use the intermediates variables.
What you have tried, get the size, it must be stored in variables [a;b], if you directly tried another function (transpose) without store it, how can you do that.
--------
A=rand(2);
[a b]=size(A');

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Pawel Cembaluk
Pawel Cembaluk 2018-10-14
Maybe size() wasn't best example here. How to deal with this one:
A=rand(2);
B=rand(2,1);
[x;y]=A*B; %incorrect
Pawel Cembaluk
Pawel Cembaluk 2018-10-14
I'm just curious if it is possible to get x and y like in this example without creating additional temporary variables (and also I don't want to replace [x;y] with a single vector).
KALYAN ACHARJYA
KALYAN ACHARJYA 2018-10-14
编辑：KALYAN ACHARJYA 2018-10-14
Check with whos, I found a very important question, Thanks for the question, learning for me also
>> A=rand(2);
B=rand(2,1);
>> C=A*B;
>> y=[6;7];
>> whos
Name Size Bytes Class Attributes
A 2x2 32 double
B 2x1 16 double
C 2x1 16 double
y 2x1 16 double

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Walter Roberson
Walter Roberson 2018-10-14

0 个投票

You should have a look at deal() -- though if you do not use a temporary variable then it helps to use an auxiliary function
expand_cell = @(C) C{:};
[x, y] = expand_cell( num2cell( A* B) );

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