[metapost] metapost tfm bug with mfplain

[Karel Horák]

Daniel H. Luecking napsal(a):
>  Karel <horakk at math.cas.cz> wrote:
>
>   
>> To make things easier, I changed all the graphics into trivial
>> rectangles, the incorrect dimensions are still there in case of chars 44
>> and 45 (octal 36 and 37). The height of these two characters is much
>> smaller than their width but should be higher!
>>     
>
> I think you mean octal 44 and 45 (which are decimal 36 and 37).
>   
It depends on the reading, I wanted to say octals of decimals 36 and 37 :-)
> I'm just guessing here, but when metaFONT writes a tfm file, all the 
> dimensions are required to be less than 4096.0. It is possible metaPOST 
> uses the same code for creating the tfm file and makes the same 
> requirement. In character 36,
>     show  h; 
> produces 7935.29486. It is possible that bits above the twefth are 
> ignored and so 7935.29486 - 4096 = 3839.29486 would be used. Or it 
> is possible some other truncation method is used. 
>
> There is another factor that might be at work here: there is a limit on 
> the number of different character heights there can be in a tfm file. If 
> there are more than 15, some will be adjusted so that there are only 15. 
> Your file seems to have 18 different heights. A similar limit is imposed on 
> depths and widths.
>
>   
You are of course true, but metafont gives correct tfm with some changes 
of heights but those are neglectable (some charht values had to be 
adjusted by as much as 1.10536pt). On the other hand metapost does not 
give any information about changing the heights at all.

Originally I generated metrics with metafont but preparing now a new 
edition of textbook I thought that it is not more necessary to compile 
the source twice:-)

All the best,
Karel


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