[Numpy-discussion] unexpected behavior with allclose( scalar, empty array)

Charles R Harris charlesr.harris@gmail....
Thu Jan 3 16:25:57 CST 2008


On Jan 3, 2008 2:37 PM, Matthew Brett <matthew.brett@gmail.com> wrote:

> Just to ask - is there a reason why this:
>
> > In [39]: all([])
> > Out[39]: True
>
> is the case?


Because it's True. Anything is true about the elements of an empty set,
because there aren't any. In this case, all asks if all elements in [] are
true, i.e., does x member [] -> x is true. Since x member [] is always
false, the implication is always true. Recall that the statement x -> y has
the same truth value as the statement x' or xy.

Chuck
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