[metapost] The numbersystem internal.

[Taco Hoekwater]

Hi Dan,

On 15 Jan 2014, at 21:49, Daniel H. Luecking <luecking at uark.edu> wrote:

> Three things:
> 
> 1. At the (windows 7) command line one can activate double precision in 
> metapost with
>    mpost -numbersystem="double" file
> However
>    mpost -s numbersystem="double" file
> produces a warning and the "scaled" value is assigned. It seems it 
> needs to be
>    mpost -s numbersystem=\"double\"
> Windows normally lets a program do its own processing of double 
> quotes, and it seems curious (to me) that mpost handles them 
> differently in the two cases. I suppose the reason is obvious to 
> experienced programmers…

That is because the quotes need to survive the command line 
parsing routines. I can look and see if it is something metapost
can solve (in a portable way).

> 2. Changing the value of the string numbersystem within a file has 
> no effect (on the number system), but metapost will not complain and 
> will in fact change the value.

That is bad, I did not realise. In the next release, there will be an
error on attempts to assign to ‘numbersystem’.

> 3. What are the number systems "binary" and "decimal" mentioned in
> mpost --help? Are they just other names for "double"? They seem to 
> have the same effect in some (very simple) tests.

They are placeholders for the two extra formats planned for metapost 2.0:
binary = arbitrary precision with base 2, decimal = arbitrary precision 
with base 10.

Best wishes,
Taco