[metapost] [NTG-context] MetaPost transformation

[Hans Hagen]

On 30-5-2012 23:10, Troy Henderson wrote:
> I've encountered a MetaPost issue, and since many MetaPost users also use
> ConTeXt (and vice-versa), I am posting this question on both lists.
>
> The command
>
>> show identity rotated 270 yscaled 0.5;
>
> outputs
>
> (0,0,0,1,-0.5,0)
>
> as expected, while the command
>
>> show identity transformed (0,0,0,1,-0.5,0);
>
> errors with
>
> ---
> ! Missing `)' has been inserted.
> <to be read again>
>                     ,
> l.26 ^^Ishow identity transformed (0,0,0,1,
>                                             -0.5,0);
> ---
>
> I am using MetaPost 1.504, and the problem seems to be that MetaPost does
> not like me using the sextuple (0,0,0,1,-0.5,0) directly, but this is the
> most convenient method for me to describe my transformations.  Is this a
> bug in MetaPost, or am I not allowed to use transformations directly with
> sextuples?

It looks like sextuples are no basic datatype. I think that the show is 
just a way to output the internal representation. Of course it would 
make sense to have sixtuples (I can even think of a generic n-tuple).

Hans

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