Any idea why all([]) is true while any([]) is false

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Khaled Hamed
Khaled Hamed 2012-7-29
>> all([])
ans =
1
>> any([])
ans =
0
  2 个评论
Ryan
Ryan 2012-7-29
It's written into the documentation as such, but no explanation is given.
Khaled Hamed
Khaled Hamed 2012-7-29
I have just noticed the same with Nan! more confusing
>> all(nan)
ans =
1
>> any(nan)
ans =
0

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采纳的回答

Daniel Shub
Daniel Shub 2012-7-29
This post by Loren lead to some comments that address the issue, especially the one by Matt Fig.

更多回答（1 个）

the cyclist
the cyclist 2012-7-29
I can't say I know definitively, but I expect that one reason is for consistency when taking the union of sets with the empty set. For example, one would want
all(union(true,[]))
to be true, and also
any(union(false,[]))
to be false. The definitions in your question make sense in that context.

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