[metapost] New numbersystems for the graph package?

Densing Martin (PSI) martin.densing at psi.ch
Mon Feb 18 09:21:04 CET 2019

Dear Luigi,

Thanks for your answer!

This removes the error, but it destroys the y-axis (no negative labels anymore).

>From my limited perspective, the problem seems to be: The graph-macro depends in several places on the finite, original numbersystem because of the Mlog transformation (which would be not needed with higher precision arithmetic). 
Until there is a fix, perhaps an innocent user should be made aware by a conditional errormessage based on the numbersystem at the beginning of the graph-macro, or a note in the documentation?


From: luigi scarso <luigi.scarso at gmail.com> 
Sent: Samstag, 16. Februar 2019 19:49
Cc: metapost at tug.org
Subject: Re: [metapost] New numbersystems for the graph package?

On Sat, Feb 16, 2019 at 3:37 PM Densing Martin (PSI) <mailto:martin.densing at psi.ch> wrote:
Dear metapost experts,

Many thanks to the metapost-coders for the introduction of the new numbersystems!

How can we ensure that the new numbersystems work with the existing, very helpful macros that are available with the usual TeX-disitributions? Most relevant would be the graph macros of John Hobby. Hence: Would it be possible to make the graph macros (and all the auxiliary macros, e.g. format etc.) work with all numbersystems?


"mpost -numbersystem=decimal http://test.mp" gives an error on the following file "http://test.mp", whereas just "mpost http://test.mp" runs smoothly. Version: MetaPost 2.000 (TeX Live 2017/W32TeX) on MS Windows.

File: http://test.mp
% 0  1.4
% 1  3.2
% 2  -4.5
% 3  8.0
% 4  9.0
% 5  4.0

% Data-file for graph can be included at beginning of source-file,
% because %<space>0 1.4 etc. is read by gdata marco until empty line

input graph

prologues := 3;
outputtemplate := "%j-%c.mps";

  draw begingraph(10cm,10cm);
    path p;
    gdata("http://test.mp", $, augment.p(i, scantokens $2););
    gdraw p;

-----------------end file

Metapost's log (if numbersystem=decimal):

! Logarithm of -7000.000523787821841175847573036896 has been replaced by 0.

This is just one of several issues, for example the auxiliary "format" macro has also problems with the new numbersystems.

Thank you very much for your help.

vardef Mabs primary x = x*.5*2 enddef;

Can you try with 
vardef Mabs primary x = x*1 enddef;


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