type if x is a square matrix statement

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Zhuoying Lin
Zhuoying Lin 2017-10-26
评论： michio 2017-10-27
Hi, How do I write the script for "If x is a square matrix funcz will be the 0"?
Thanks!
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Jan
Jan 2017-10-27
A bullet-proof solution is not trivial. Therefore this question is more interesting than it looks like on first glance.

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回答（3 个）

Stephen23
Stephen23 2017-10-26
编辑：Stephen23 2017-10-26
funcz = ~diff(size(x))
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Stephen23
Stephen23 2017-10-26
@Jan Simon: thank you, that is a tidy solution for ND arrays.
Zhuoying Lin
Zhuoying Lin 2017-10-26
Never thought about this question can be such complex. I just start learning Matlab and THANK YOU all for your answers!

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Jan
Jan 2017-10-26
编辑：Jan 2017-10-26
funcz = ~ismatrix(x) || (size(x, 1) ~= size(x, 2));
or with Matlab versions before R2010b:
funcz = (ndims(x) ~= 2) || (size(x, 1) ~= size(x, 2));
This rejects [0 x 1] matrices, but is is questionable, if an empty matrix can be non-square.
To reply funcz=0 for vectors:
funcz = (ndims(x) ~= 2) || all(size(x) ~= 1);
or with modern Matlab versions:
funcz = ~isvector(x)
michio
michio 2017-10-26
[nRow,nCol] = size(x);
if nRow == nCol
funcz = 0;
end
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Jan
Jan 2017-10-26
编辑：Jan 2017-10-26
This fails for a [4,2,2] array:
[nR, nC] = size(rand(4, 2, 2))
nR = 4, nC = 4
michio
michio 2017-10-27
Yes, it assumes that the array is 2D. Interesting thread :)

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