if we use the instruction [~, idx]=sort(abs(A(:))), what is this ~ (NOT) sign represents

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studentambitious
studentambitious 2016-4-27
编辑： Stephen23 2016-4-27
Can we replace ~ with any other name

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回答（2 个）

Azzi Abdelmalek
Azzi Abdelmalek 2016-4-27
编辑：Azzi Abdelmalek 2016-4-27
[e, idx]=sort([2 1 5 8 6])
will return
e= [1 2 5 6 8]
idx=[2 1 3 5 4]
[~, idx]=sort([2 1 5 8 6]
will return just idx. In this case, ~ is not considered as "not" operator
Jan
Jan 2016-4-27
For backward compatibiliy I do not use the tilde ~, but a variable called "dummy".
  2 个评论
Jan
Jan 2016-4-27
Beside 2015b I'm still using R6.5 and R2009a. While avoiding the tilde is trivial, catch exception required an ugly workaround for R6.5: catch ME_, ME = ME_. And under the historical Matlab a folder is included in the path, which defines the funktion ME_:
function Exception = ME_
persistent LastException
if nargout == 0
LastException = lasterror();
LastException.cause = {};
end
Exception = LastException;
I've backported the standard algebraic methods for single's, typecast, cast, uigetfiles, ancestor, commandwindow, javacomponent, javaObjectEDT.
The reason to maintain such an old system like R6.5 is an extremely well tested large code (>300'000 lines + comments) for clinical decision making and the need to guarantee the reproducibility of the results for 10 years. Fortunately the retirement of WindowsXP allows to skip R6.5 now :-) Bye bye, my beloved dinosaur.
Let me mention that R6.5 runs much faster in a VM with XP than 2015b on the real processor.

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