[GAP Forum] Strange output

[Dmitrii (Dima) Pasechnik]

On 10 February 2013 10:52, Gordon Royle <gordon.royle at uwa.edu.au> wrote:
> Well, thanks for the feedback, but I remain somewhat confused…

I think this is definitely a bug, and must be fixed ASAP...

Best,
Dima

>
> Firstly,  why does GAP unilaterally choose to change the format .. .the program is simply a recursive program with a single Print statement, and yet the output changes format , and then changes back again, without me asking it to...
>
> [ 1, 5, 51 ]
> [ 1, 6 .. 11 ]
> [ 1, 6, 12 ]
>
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> Secondly, why is
>
> 6 .. 11
>
> the "range representation" for
>
> 6, 11
>
> In most languages that support it, the ".." means "everything from the first to the last (or perhaps the first to the last-minus-one)"
>
>
> Actually, it means the same in GAP too:
>
> gap> for x in [6 .. 11] do
>> Print(x," ");
>> od;
> 6 7 8 9 10 11
>
> So, naively I would expect
>
> [1, 6 .. 11]
>
> to be a fancy way of saying
>
> [1, 6, 7, 8, 9, 10, 11]
>
>
> But it's not:
>
> gap> for x in [1, 6 .. 11] do
>> Print(x," ");
>> od;
> 1 6 11
>
>
> It seems dangerous to me to have the expression   a .. b mean something different to (a) other uses in the same language, (b) mathematical usage and (c ) other programming languages.
>
>
> Thirdly, why has this happened RIGHT NOW, when I've been using this program for years without ever seeing anything like this before…
>
>
> Thanks again
>
> Gordon
>
>
>
> Professor Gordon Royle
> School of Mathematics and Statistics
> University of Western Australia
> Gordon.Royle at uwa.edu.au<mailto:Gordon.Royle at uwa.edu.au>
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